// File: /contracts/opensea/ERC1155Tradable.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0; 

import "@openzeppelin/contracts/utils/Strings.sol";

import './IERC1155Tradable.sol';
import './ERC1155.sol';
import './ERC1155Metadata.sol';
import './ERC1155MintBurn.sol';
import "../Ownable.sol";
 
contract OwnableDelegateProxy { }

contract ProxyRegistry {
  mapping(address => OwnableDelegateProxy) public proxies;
}

/**
 * @title ERC1155Tradable
 * ERC1155Tradable - ERC1155 contract that whitelists an operator address, has create and mint functionality, and supports useful standards from OpenZeppelin,
  like _exists(), name(), symbol(), and totalSupply()
 */
contract ERC1155Tradable is IERC1155Tradable, ERC1155, ERC1155MintBurn, ERC1155Metadata, Ownable {
  using Strings for uint256;

  address proxyRegistryAddress;
  uint256 private _currentTokenID;
  mapping (uint256 => address) public creators;
  mapping (uint256 => uint256) public tokenSupply;

  mapping(address => bool) public isAllowedToCreate;
  // Contract name
  string public name;
  // Contract symbol
  string public symbol;

  /**
   * @dev Require_msgSender() to be the creator of the token id
   */
  modifier creatorOnly(uint256 _id) {
    require(creators[_id] ==_msgSender() && isAllowedToCreate[_msgSender()], "ERC1155Tradable#creatorOnly: ONLY_CREATOR_ALLOWED");
    _;
  }

  /**
   * @dev Require_msgSender() to own more than 0 of the token id
   */
  modifier ownersOnly(uint256 _id) {
    require(balances[msg.sender][_id] > 0, "ERC1155Tradable#ownersOnly: ONLY_OWNERS_ALLOWED");
    _;
  }

  constructor(
    string memory _name,
    string memory _symbol,
    string memory _metadataURI,
    address _proxyRegistryAddress,
    address owner
  ) Ownable(owner) {
    name = _name;
    symbol = _symbol;
    proxyRegistryAddress = _proxyRegistryAddress;
    isAllowedToCreate[owner] = true;
    _setBaseMetadataURI(_metadataURI);
  }

  function uri(
    uint256 _id
  ) public view override returns (string memory) {
    require(_exists(_id), "ERC721Tradable#uri: NONEXISTENT_TOKEN");
    return bytes(baseMetadataURI).length > 0 ? string(abi.encodePacked(baseMetadataURI, _id.toString())) : "";
  }

  /**
    * @dev Returns the total quantity for a token ID
    * @param _id uint256 ID of the token to query
    * @return amount of token in existence
    */
  function totalSupply(
    uint256 _id
  ) public view returns (uint256) {
    return tokenSupply[_id];
  }

  /**
   * @dev Will update the base URL of token's URI
   * @param _newBaseMetadataURI New base URL of token's URI
   */
  function setBaseMetadataURI(
    string memory _newBaseMetadataURI
  ) public onlyOwner {
    _setBaseMetadataURI(_newBaseMetadataURI);
  }

  /**
  * @dev Sets address allowed to create 
  * @param _account account to allow/disallow
  * @param _allow true to allow, false to remove
  */
  function setAllowToCreate(address _account, bool _allow) public onlyOwner {
    isAllowedToCreate[_account] = _allow;
  }

  /**
    * @dev Creates a new token type and assigns _initialSupply to an address
    * NOTE: remove onlyOwner if you want third parties to create new tokens on your contract (which may change your IDs)
    * @param _initialOwner address of the first owner of the token
    * @param _initialSupply amount to supply the first owner
    * @return The newly created token ID
    */
  function create(
    address _initialOwner,
    uint256 _initialSupply
  ) external override returns (uint256) {
    require(isAllowedToCreate[_msgSender()], "Not allowed");

    uint256 _id = getNextTokenID(); 
    _incrementTokenTypeId();
    creators[_id] =_msgSender();

    _mint(_initialOwner, _id, _initialSupply, "");
    tokenSupply[_id] = _initialSupply;
    return _id;
  }

  /**
    * @dev Mints some amount of tokens to an address
    * @param _to          Address of the future owner of the token
    * @param _id          Token ID to mint
    * @param _quantity    Amount of tokens to mint
    */
  function mint(
    address _to,
    uint256 _id,
    uint256 _quantity
  ) public override creatorOnly(_id) {
    _mint(_to, _id, _quantity, "");
    tokenSupply[_id] += _quantity;
  }

  /**
    * @dev Mint tokens for each id in _ids
    * @param _to          The address to mint tokens to
    * @param _ids         Array of ids to mint
    * @param _quantities  Array of amounts of tokens to mint per id
    */
  function batchMint(
    address _to,
    uint256[] memory _ids,
    uint256[] memory _quantities
  ) public override {
    for (uint256 i = 0; i < _ids.length; i++) {
      uint256 _id = _ids[i];
      require(creators[_id] ==_msgSender(), "ERC1155Tradable#batchMint: ONLY_CREATOR_ALLOWED");
      uint256 quantity = _quantities[i];
      tokenSupply[_id] += quantity;
    }
    _batchMint(_to, _ids, _quantities, "");
  }

  /**
    * @dev Change the creator address for given tokens
    * @param _to   Address of the new creator
    * @param _ids  Array of Token IDs to change creator
    */
  function setCreator(
    address _to,
    uint256[] memory _ids
  ) public override {
    require(_to != address(0), "ERC1155Tradable#setCreator: INVALID_ADDRESS.");
    for (uint256 i = 0; i < _ids.length; i++) {
      uint256 id = _ids[i];
      _setCreator(_to, id);
    }
  }

  /**
   * Override isApprovedForAll to whitelist user's OpenSea proxy accounts to enable gas-free listings.
   */
  function isApprovedForAll(
    address _owner,
    address _operator
  ) public override(ERC1155, IERC1155) view returns (bool isOperator) {
    // Whitelist OpenSea proxy contract for easy trading.
    ProxyRegistry proxyRegistry = ProxyRegistry(proxyRegistryAddress);
    if (address(proxyRegistry.proxies(_owner)) == _operator) {
      return true;
    }

    return ERC1155.isApprovedForAll(_owner, _operator);
  }

  /**
    * @dev Change the creator address for given token
    * @param _to   Address of the new creator
    * @param _id  Token IDs to change creator of
    */
  function _setCreator(address _to, uint256 _id) internal creatorOnly(_id)
  {
      creators[_id] = _to;
  }

  /**
    * @dev Returns whether the specified token exists by checking to see if it has a creator
    * @param _id uint256 ID of the token to query the existence of
    * @return bool whether the token exists
    */
  function _exists(
    uint256 _id
  ) internal view returns (bool) {
    return creators[_id] != address(0);
  }

  /**
    * @dev calculates the next token ID based on value of _currentTokenID
    * @return uint256 for the next token ID
    */
  function getNextTokenID() public view returns (uint256) {
    return _currentTokenID + 1;
  }

  /**
    * @dev increments the value of _currentTokenID
    */
  function _incrementTokenTypeId() private  {
    _currentTokenID++;
  }


  /***********************************|
  |          ERC165 Functions         |
  |__________________________________*/

  /**
   * @notice Query if a contract implements an interface
   * @param _interfaceID  The interface identifier, as specified in ERC-165
   * @return `true` if the contract implements `_interfaceID` and
   */
  function supportsInterface(bytes4 _interfaceID) public override(ERC1155, ERC1155Metadata) virtual view returns (bool) {
    if (_interfaceID == type(IERC1155).interfaceId || _interfaceID == type(IERC1155Tradable).interfaceId) {
      return true;
    }
    return super.supportsInterface(_interfaceID);
  }
  
}
// File: /contracts/Ownable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts//utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor(address newOwner) {
        _setOwner(newOwner);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: /contracts/opensea/IERC1155.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.0;


interface IERC1155 {

  /****************************************|
  |                 Events                 |
  |_______________________________________*/

  /**
   * @dev Either TransferSingle or TransferBatch MUST emit when tokens are transferred, including zero amount transfers as well as minting or burning
   *   Operator MUST be msg.sender
   *   When minting/creating tokens, the `_from` field MUST be set to `0x0`
   *   When burning/destroying tokens, the `_to` field MUST be set to `0x0`
   *   The total amount transferred from address 0x0 minus the total amount transferred to 0x0 may be used by clients and exchanges to be added to the "circulating supply" for a given token ID
   *   To broadcast the existence of a token ID with no initial balance, the contract SHOULD emit the TransferSingle event from `0x0` to `0x0`, with the token creator as `_operator`, and a `_amount` of 0
   */
  event TransferSingle(address indexed _operator, address indexed _from, address indexed _to, uint256 _id, uint256 _amount);

  /**
   * @dev Either TransferSingle or TransferBatch MUST emit when tokens are transferred, including zero amount transfers as well as minting or burning
   *   Operator MUST be msg.sender
   *   When minting/creating tokens, the `_from` field MUST be set to `0x0`
   *   When burning/destroying tokens, the `_to` field MUST be set to `0x0`
   *   The total amount transferred from address 0x0 minus the total amount transferred to 0x0 may be used by clients and exchanges to be added to the "circulating supply" for a given token ID
   *   To broadcast the existence of multiple token IDs with no initial balance, this SHOULD emit the TransferBatch event from `0x0` to `0x0`, with the token creator as `_operator`, and a `_amount` of 0
   */
  event TransferBatch(address indexed _operator, address indexed _from, address indexed _to, uint256[] _ids, uint256[] _amounts);

  /**
   * @dev MUST emit when an approval is updated
   */
  event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);


  /****************************************|
  |                Functions               |
  |_______________________________________*/

  /**
    * @notice Transfers amount of an _id from the _from address to the _to address specified
    * @dev MUST emit TransferSingle event on success
    * Caller must be approved to manage the _from account's tokens (see isApprovedForAll)
    * MUST throw if `_to` is the zero address
    * MUST throw if balance of sender for token `_id` is lower than the `_amount` sent
    * MUST throw on any other error
    * When transfer is complete, this function MUST check if `_to` is a smart contract (code size > 0). If so, it MUST call `onERC1155Received` on `_to` and revert if the return amount is not `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
    * @param _from    Source address
    * @param _to      Target address
    * @param _id      ID of the token type
    * @param _amount  Transfered amount
    * @param _data    Additional data with no specified format, sent in call to `_to`
    */
  function safeTransferFrom(address _from, address _to, uint256 _id, uint256 _amount, bytes calldata _data) external;

  /**
    * @notice Send multiple types of Tokens from the _from address to the _to address (with safety call)
    * @dev MUST emit TransferBatch event on success
    * Caller must be approved to manage the _from account's tokens (see isApprovedForAll)
    * MUST throw if `_to` is the zero address
    * MUST throw if length of `_ids` is not the same as length of `_amounts`
    * MUST throw if any of the balance of sender for token `_ids` is lower than the respective `_amounts` sent
    * MUST throw on any other error
    * When transfer is complete, this function MUST check if `_to` is a smart contract (code size > 0). If so, it MUST call `onERC1155BatchReceived` on `_to` and revert if the return amount is not `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
    * Transfers and events MUST occur in the array order they were submitted (_ids[0] before _ids[1], etc)
    * @param _from     Source addresses
    * @param _to       Target addresses
    * @param _ids      IDs of each token type
    * @param _amounts  Transfer amounts per token type
    * @param _data     Additional data with no specified format, sent in call to `_to`
  */
  function safeBatchTransferFrom(address _from, address _to, uint256[] calldata _ids, uint256[] calldata _amounts, bytes calldata _data) external;

  /**
   * @notice Get the balance of an account's Tokens
   * @param _owner  The address of the token holder
   * @param _id     ID of the Token
   * @return        The _owner's balance of the Token type requested
   */
  function balanceOf(address _owner, uint256 _id) external view returns (uint256);

  /**
   * @notice Get the balance of multiple account/token pairs
   * @param _owners The addresses of the token holders
   * @param _ids    ID of the Tokens
   * @return        The _owner's balance of the Token types requested (i.e. balance for each (owner, id) pair)
   */
  function balanceOfBatch(address[] calldata _owners, uint256[] calldata _ids) external view returns (uint256[] memory);

  /**
   * @notice Enable or disable approval for a third party ("operator") to manage all of caller's tokens
   * @dev MUST emit the ApprovalForAll event on success
   * @param _operator  Address to add to the set of authorized operators
   * @param _approved  True if the operator is approved, false to revoke approval
   */
  function setApprovalForAll(address _operator, bool _approved) external;

  /**
   * @notice Queries the approval status of an operator for a given owner
   * @param _owner     The owner of the Tokens
   * @param _operator  Address of authorized operator
   * @return isOperator True if the operator is approved, false if not
   */
  function isApprovedForAll(address _owner, address _operator) external view returns (bool isOperator);
}

// File: /contracts/opensea/IERC1155Tradable.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "./IERC1155.sol";

interface IERC1155Tradable is IERC1155 {

    function create(address _initialOwner, uint256 _initialSupply) external returns (uint256);

    function mint(address _to, uint256 _id, uint256 _quantity) external;

    function batchMint( address _to, uint256[] memory _ids, uint256[] memory _quantities) external;

    function setCreator(address _to, uint256[] memory _ids) external;
}
// File: /contracts/opensea/ERC1155MintBurn.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0; 

import "./ERC1155.sol";


/**
 * @dev Multi-Fungible Tokens with minting and burning methods. These methods assume
 *      a parent contract to be executed as they are `internal` functions
 */
contract ERC1155MintBurn is ERC1155 {
  using SafeMath for uint256;

  /****************************************|
  |            Minting Functions           |
  |_______________________________________*/

  /**
   * @notice Mint _amount of tokens of a given id
   * @param _to      The address to mint tokens to
   * @param _id      Token id to mint
   * @param _amount  The amount to be minted
   * @param _data    Data to pass if receiver is contract
   */
  function _mint(address _to, uint256 _id, uint256 _amount, bytes memory _data)
    internal
  {
    // Add _amount
    balances[_to][_id] = balances[_to][_id].add(_amount);

    // Emit event
    emit TransferSingle(msg.sender, address(0x0), _to, _id, _amount);

    // Calling onReceive method if recipient is contract
    _callonERC1155Received(address(0x0), _to, _id, _amount, gasleft(), _data);
  }

  /**
   * @notice Mint tokens for each ids in _ids
   * @param _to       The address to mint tokens to
   * @param _ids      Array of ids to mint
   * @param _amounts  Array of amount of tokens to mint per id
   * @param _data    Data to pass if receiver is contract
   */
  function _batchMint(address _to, uint256[] memory _ids, uint256[] memory _amounts, bytes memory _data)
    internal
  {
    require(_ids.length == _amounts.length, "ERC1155MintBurn#batchMint: INVALID_ARRAYS_LENGTH");

    // Number of mints to execute
    uint256 nMint = _ids.length;

     // Executing all minting
    for (uint256 i = 0; i < nMint; i++) {
      // Update storage balance
      balances[_to][_ids[i]] = balances[_to][_ids[i]].add(_amounts[i]);
    }

    // Emit batch mint event
    emit TransferBatch(msg.sender, address(0x0), _to, _ids, _amounts);

    // Calling onReceive method if recipient is contract
    _callonERC1155BatchReceived(address(0x0), _to, _ids, _amounts, gasleft(), _data);
  }


  /****************************************|
  |            Burning Functions           |
  |_______________________________________*/

  /**
   * @notice Burn _amount of tokens of a given token id
   * @param _from    The address to burn tokens from
   * @param _id      Token id to burn
   * @param _amount  The amount to be burned
   */
  function _burn(address _from, uint256 _id, uint256 _amount)
    internal
  {
    //Substract _amount
    balances[_from][_id] = balances[_from][_id].sub(_amount);

    // Emit event
    emit TransferSingle(msg.sender, _from, address(0x0), _id, _amount);
  }

  /**
   * @notice Burn tokens of given token id for each (_ids[i], _amounts[i]) pair
   * @param _from     The address to burn tokens from
   * @param _ids      Array of token ids to burn
   * @param _amounts  Array of the amount to be burned
   */
  function _batchBurn(address _from, uint256[] memory _ids, uint256[] memory _amounts)
    internal
  {
    // Number of mints to execute
    uint256 nBurn = _ids.length;
    require(nBurn == _amounts.length, "ERC1155MintBurn#batchBurn: INVALID_ARRAYS_LENGTH");

    // Executing all minting
    for (uint256 i = 0; i < nBurn; i++) {
      // Update storage balance
      balances[_from][_ids[i]] = balances[_from][_ids[i]].sub(_amounts[i]);
    }

    // Emit batch mint event
    emit TransferBatch(msg.sender, _from, address(0x0), _ids, _amounts);
  }
}

// File: /contracts/opensea/ERC1155Metadata.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "./IERC1155Metadata.sol";
import "@openzeppelin/contracts/utils/introspection/ERC165.sol";


/**
 * @notice Contract that handles metadata related methods.
 * @dev Methods assume a deterministic generation of URI based on token IDs.
 *      Methods also assume that URI uses hex representation of token IDs.
 */
contract ERC1155Metadata is IERC1155Metadata, ERC165 {
  // URI's default URI prefix
  string internal baseMetadataURI;

  /***********************************|
  |     Metadata Public Function s    |
  |__________________________________*/

  /**
   * @notice A distinct Uniform Resource Identifier (URI) for a given token.
   * @dev URIs are defined in RFC 3986.
   *      URIs are assumed to be deterministically generated based on token ID
   * @return URI string
   */
  function uri(uint256 _id) public virtual override view returns (string memory) {
    return string(abi.encodePacked(baseMetadataURI, _uint2str(_id), ".json"));
  }

  /**
   * @notice Will update the base URL of token's URI
   * @param _newBaseMetadataURI New base URL of token's URI
   */
  function _setBaseMetadataURI(string memory _newBaseMetadataURI) internal {
    baseMetadataURI = _newBaseMetadataURI;
  }

  /**
   * @notice Query if a contract implements an interface
   * @param _interfaceID  The interface identifier, as specified in ERC-165
   * @return `true` if the contract implements `_interfaceID` and
   */
  function supportsInterface(bytes4 _interfaceID) public override virtual view returns (bool) {
    if (_interfaceID == type(IERC1155Metadata).interfaceId) {
      return true;
    }
    return super.supportsInterface(_interfaceID);
  }


  /***********************************|
  |    Utility Internal Functions     |
  |__________________________________*/

  /**
   * @notice Convert uint256 to string
   * @param _i Unsigned integer to convert to string
   */
  function _uint2str(uint256 _i) internal pure returns (string memory _uintAsString) {
    if (_i == 0) {
      return "0";
    }

    uint256 j = _i;
    uint256 ii = _i;
    uint256 len;

    // Get number of bytes
    while (j != 0) {
      len++;
      j /= 10;
    }

    bytes memory bstr = new bytes(len);
    uint256 k = len - 1;

    // Get each individual ASCII
    while (ii != 0) {
      bstr[k--] = bytes1(uint8(48 + ii % 10));
      ii /= 10;
    }

    // Convert to string
    return string(bstr);
  }
}

// File: /contracts/opensea/ERC1155.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.0;

import "./IERC1155.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC1155/IERC1155Receiver.sol";
import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/utils/introspection/ERC165.sol";


/**
 * @dev Implementation of Multi-Token Standard contract
 */
contract ERC1155 is IERC1155, ERC165 {
  using SafeMath for uint256;
  using Address for address;

  /***********************************|
  |        Variables and Events       |
  |__________________________________*/

  // onReceive function signatures
  bytes4 constant internal ERC1155_RECEIVED_VALUE = 0xf23a6e61;
  bytes4 constant internal ERC1155_BATCH_RECEIVED_VALUE = 0xbc197c81;

  // Objects balances
  mapping (address => mapping(uint256 => uint256)) internal balances;

  // Operator Functions
  mapping (address => mapping(address => bool)) internal operators;


  /***********************************|
  |     Public Transfer Functions     |
  |__________________________________*/

  /**
   * @notice Transfers amount amount of an _id from the _from address to the _to address specified
   * @param _from    Source address
   * @param _to      Target address
   * @param _id      ID of the token type
   * @param _amount  Transfered amount
   * @param _data    Additional data with no specified format, sent in call to `_to`
   */
  function safeTransferFrom(address _from, address _to, uint256 _id, uint256 _amount, bytes memory _data)
    public override
  {
    require((msg.sender == _from) || isApprovedForAll(_from, msg.sender), "ERC1155#safeTransferFrom: INVALID_OPERATOR");
    require(_to != address(0),"ERC1155#safeTransferFrom: INVALID_RECIPIENT");
    // require(_amount <= balances[_from][_id]) is not necessary since checked with safemath operations

    _safeTransferFrom(_from, _to, _id, _amount);
    _callonERC1155Received(_from, _to, _id, _amount, gasleft(), _data);
  }

  /**
   * @notice Send multiple types of Tokens from the _from address to the _to address (with safety call)
   * @param _from     Source addresses
   * @param _to       Target addresses
   * @param _ids      IDs of each token type
   * @param _amounts  Transfer amounts per token type
   * @param _data     Additional data with no specified format, sent in call to `_to`
   */
  function safeBatchTransferFrom(address _from, address _to, uint256[] memory _ids, uint256[] memory _amounts, bytes memory _data)
    public override
  {
    // Requirements
    require((msg.sender == _from) || isApprovedForAll(_from, msg.sender), "ERC1155#safeBatchTransferFrom: INVALID_OPERATOR");
    require(_to != address(0), "ERC1155#safeBatchTransferFrom: INVALID_RECIPIENT");

    _safeBatchTransferFrom(_from, _to, _ids, _amounts);
    _callonERC1155BatchReceived(_from, _to, _ids, _amounts, gasleft(), _data);
  }


  /***********************************|
  |    Internal Transfer Functions    |
  |__________________________________*/

  /**
   * @notice Transfers amount amount of an _id from the _from address to the _to address specified
   * @param _from    Source address
   * @param _to      Target address
   * @param _id      ID of the token type
   * @param _amount  Transfered amount
   */
  function _safeTransferFrom(address _from, address _to, uint256 _id, uint256 _amount)
    internal
  {
    // Update balances
    balances[_from][_id] = balances[_from][_id].sub(_amount); // Subtract amount
    balances[_to][_id] = balances[_to][_id].add(_amount);     // Add amount

    // Emit event
    emit TransferSingle(msg.sender, _from, _to, _id, _amount);
  }

  /**
   * @notice Verifies if receiver is contract and if so, calls (_to).onERC1155Received(...)
   */
  function _callonERC1155Received(address _from, address _to, uint256 _id, uint256 _amount, uint256 /*_gasLimit*/, bytes memory _data)
    internal
  {
    if (_to.isContract()) {
        try IERC1155Receiver(_to).onERC1155Received(msg.sender, _from, _id, _amount, _data) returns (bytes4 response) {

            if (response != IERC1155Receiver.onERC1155Received.selector) {
                revert("ERC1155: ERC1155Receiver rejected tokens");
            }
        } catch Error(string memory reason) {
            revert(reason);
        } catch {
            revert("ERC1155: transfer to non ERC1155Receiver implementer");
        }
    }
  }

  /**
   * @notice Send multiple types of Tokens from the _from address to the _to address (with safety call)
   * @param _from     Source addresses
   * @param _to       Target addresses
   * @param _ids      IDs of each token type
   * @param _amounts  Transfer amounts per token type
   */
  function _safeBatchTransferFrom(address _from, address _to, uint256[] memory _ids, uint256[] memory _amounts)
    internal
  {
    require(_ids.length == _amounts.length, "ERC1155#_safeBatchTransferFrom: INVALID_ARRAYS_LENGTH");

    // Number of transfer to execute
    uint256 nTransfer = _ids.length;

    // Executing all transfers
    for (uint256 i = 0; i < nTransfer; i++) {
      // Update storage balance of previous bin
      balances[_from][_ids[i]] = balances[_from][_ids[i]].sub(_amounts[i]);
      balances[_to][_ids[i]] = balances[_to][_ids[i]].add(_amounts[i]);
    }

    // Emit event
    emit TransferBatch(msg.sender, _from, _to, _ids, _amounts);
  }

  /**
   * @notice Verifies if receiver is contract and if so, calls (_to).onERC1155BatchReceived(...)
   */
  function _callonERC1155BatchReceived(address _from, address _to, uint256[] memory _ids, uint256[] memory _amounts, uint256 /*_gasLimit*/, bytes memory _data)
    internal
  {

    if (_to.isContract()) {
        try IERC1155Receiver(_to).onERC1155BatchReceived(msg.sender, _from, _ids, _amounts, _data) returns (
            bytes4 response
        ) {
            if (response != IERC1155Receiver.onERC1155BatchReceived.selector) {
                revert("ERC1155: ERC1155Receiver rejected tokens");
            }
        } catch Error(string memory reason) {
            revert(reason);
        } catch {
            revert("ERC1155: transfer to non ERC1155Receiver implementer");
        }
    }
    // Pass data if recipient is contract
    // if (_to.isContract()) {
    //   bytes4 retval = IERC1155Receiver(_to).onERC1155BatchReceived{gas: _gasLimit}(msg.sender, _from, _ids, _amounts, _data);
    //   require(retval == ERC1155_BATCH_RECEIVED_VALUE, "ERC1155#_callonERC1155BatchReceived: INVALID_ON_RECEIVE_MESSAGE");
    // }
  }


  /***********************************|
  |         Operator Functions        |
  |__________________________________*/

  /**
   * @notice Enable or disable approval for a third party ("operator") to manage all of caller's tokens
   * @param _operator  Address to add to the set of authorized operators
   * @param _approved  True if the operator is approved, false to revoke approval
   */
  function setApprovalForAll(address _operator, bool _approved)
    external override
  {
    // Update operator status
    operators[msg.sender][_operator] = _approved;
    emit ApprovalForAll(msg.sender, _operator, _approved);
  }

  /**
   * @notice Queries the approval status of an operator for a given owner
   * @param _owner     The owner of the Tokens
   * @param _operator  Address of authorized operator
   * @return isOperator True if the operator is approved, false if not
   */
  function isApprovedForAll(address _owner, address _operator)
    public virtual override view returns (bool isOperator)
  {
    return operators[_owner][_operator];
  }


  /***********************************|
  |         Balance Functions         |
  |__________________________________*/

  /**
   * @notice Get the balance of an account's Tokens
   * @param _owner  The address of the token holder
   * @param _id     ID of the Token
   * @return The _owner's balance of the Token type requested
   */
  function balanceOf(address _owner, uint256 _id)
    public override view returns (uint256)
  {
    return balances[_owner][_id];
  }

  /**
   * @notice Get the balance of multiple account/token pairs
   * @param _owners The addresses of the token holders
   * @param _ids    ID of the Tokens
   * @return        The _owner's balance of the Token types requested (i.e. balance for each (owner, id) pair)
   */
  function balanceOfBatch(address[] memory _owners, uint256[] memory _ids)
    public override view returns (uint256[] memory)
  {
    require(_owners.length == _ids.length, "ERC1155#balanceOfBatch: INVALID_ARRAY_LENGTH");

    // Variables
    uint256[] memory batchBalances = new uint256[](_owners.length);

    // Iterate over each owner and token ID
    for (uint256 i = 0; i < _owners.length; i++) {
      batchBalances[i] = balances[_owners[i]][_ids[i]];
    }

    return batchBalances;
  }


  /***********************************|
  |          ERC165 Functions         |
  |__________________________________*/

  /**
   * @notice Query if a contract implements an interface
   * @param _interfaceID  The interface identifier, as specified in ERC-165
   * @return `true` if the contract implements `_interfaceID` and
   */
  function supportsInterface(bytes4 _interfaceID) public override(ERC165) virtual view returns (bool) {
    if (_interfaceID == type(IERC1155).interfaceId) {
      return true;
    }
    return super.supportsInterface(_interfaceID);
  }
}

// File: /contracts/opensea/IERC1155Metadata.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.0;

interface IERC1155Metadata {

  event URI(string _uri, uint256 indexed _id);

  /****************************************|
  |                Functions               |
  |_______________________________________*/

  /**
   * @notice A distinct Uniform Resource Identifier (URI) for a given token.
   * @dev URIs are defined in RFC 3986.
   *      URIs are assumed to be deterministically generated based on token ID
   *      Token IDs are assumed to be represented in their hex format in URIs
   * @return URI string
   */
  function uri(uint256 _id) external view returns (string memory);
}

// File: @openzeppelin/contracts/utils/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is no longer needed starting with Solidity 0.8. The compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: @openzeppelin/contracts/utils/Strings.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/token/ERC1155/IERC1155Receiver.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165.sol";

/**
 * @dev _Available since v3.1._
 */
interface IERC1155Receiver is IERC165 {
    /**
        @dev Handles the receipt of a single ERC1155 token type. This function is
        called at the end of a `safeTransferFrom` after the balance has been updated.
        To accept the transfer, this must return
        `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
        (i.e. 0xf23a6e61, or its own function selector).
        @param operator The address which initiated the transfer (i.e. msg.sender)
        @param from The address which previously owned the token
        @param id The ID of the token being transferred
        @param value The amount of tokens being transferred
        @param data Additional data with no specified format
        @return `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))` if transfer is allowed
    */
    function onERC1155Received(
        address operator,
        address from,
        uint256 id,
        uint256 value,
        bytes calldata data
    ) external returns (bytes4);

    /**
        @dev Handles the receipt of a multiple ERC1155 token types. This function
        is called at the end of a `safeBatchTransferFrom` after the balances have
        been updated. To accept the transfer(s), this must return
        `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
        (i.e. 0xbc197c81, or its own function selector).
        @param operator The address which initiated the batch transfer (i.e. msg.sender)
        @param from The address which previously owned the token
        @param ids An array containing ids of each token being transferred (order and length must match values array)
        @param values An array containing amounts of each token being transferred (order and length must match ids array)
        @param data Additional data with no specified format
        @return `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))` if transfer is allowed
    */
    function onERC1155BatchReceived(
        address operator,
        address from,
        uint256[] calldata ids,
        uint256[] calldata values,
        bytes calldata data
    ) external returns (bytes4);
    
}

// File: @openzeppelin/contracts//utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}