// File: contracts/F8_with_mapping_wl.sol



//FFFFFFFFFFFFFFFFFFFFFF     888888888                      TTTTTTTTTTTTTTTTTTTTTTT     OOOOOOOOO     KKKKKKKKK    KKKKKKKEEEEEEEEEEEEEEEEEEEEEENNNNNNNN        NNNNNNNN
//F::::::::::::::::::::F   88:::::::::88                    T:::::::::::::::::::::T   OO:::::::::OO   K:::::::K    K:::::KE::::::::::::::::::::EN:::::::N       N::::::N
//F::::::::::::::::::::F 88:::::::::::::88                  T:::::::::::::::::::::T OO:::::::::::::OO K:::::::K    K:::::KE::::::::::::::::::::EN::::::::N      N::::::N
//FF::::::FFFFFFFFF::::F8::::::88888::::::8                 T:::::TT:::::::TT:::::TO:::::::OOO:::::::OK:::::::K   K::::::KEE::::::EEEEEEEEE::::EN:::::::::N     N::::::N
//  F:::::F       FFFFFF8:::::8     8:::::8                 TTTTTT  T:::::T  TTTTTTO::::::O   O::::::OKK::::::K  K:::::KKK  E:::::E       EEEEEEN::::::::::N    N::::::N
//  F:::::F             8:::::8     8:::::8                         T:::::T        O:::::O     O:::::O  K:::::K K:::::K     E:::::E             N:::::::::::N   N::::::N
//  F::::::FFFFFFFFFF    8:::::88888:::::8                          T:::::T        O:::::O     O:::::O  K::::::K:::::K      E::::::EEEEEEEEEE   N:::::::N::::N  N::::::N
//  F:::::::::::::::F     8:::::::::::::8   ---------------         T:::::T        O:::::O     O:::::O  K:::::::::::K       E:::::::::::::::E   N::::::N N::::N N::::::N
//  F:::::::::::::::F    8:::::88888:::::8  -:::::::::::::-         T:::::T        O:::::O     O:::::O  K:::::::::::K       E:::::::::::::::E   N::::::N  N::::N:::::::N
//  F::::::FFFFFFFFFF   8:::::8     8:::::8 ---------------         T:::::T        O:::::O     O:::::O  K::::::K:::::K      E::::::EEEEEEEEEE   N::::::N   N:::::::::::N
//  F:::::F             8:::::8     8:::::8                         T:::::T        O:::::O     O:::::O  K:::::K K:::::K     E:::::E             N::::::N    N::::::::::N
//  F:::::F             8:::::8     8:::::8                         T:::::T        O::::::O   O::::::OKK::::::K  K:::::KKK  E:::::E       EEEEEEN::::::N     N:::::::::N
//FF:::::::FF           8::::::88888::::::8                       TT:::::::TT      O:::::::OOO:::::::OK:::::::K   K::::::KEE::::::EEEEEEEE:::::EN::::::N      N::::::::N
//F::::::::FF            88:::::::::::::88                        T:::::::::T       OO:::::::::::::OO K:::::::K    K:::::KE::::::::::::::::::::EN::::::N       N:::::::N
//F::::::::FF              88:::::::::88                          T:::::::::T         OO:::::::::OO   K:::::::K    K:::::KE::::::::::::::::::::EN::::::N        N::::::N
//FFFFFFFFFFF                888888888                            TTTTTTTTTTT           OOOOOOOOO     KKKKKKKKK    KKKKKKKEEEEEEEEEEEEEEEEEEEEEENNNNNNNN         NNNNNNN
//                                                                                                                                                                      
//                                                                                                                                                                      
//                                                                                                                                                                      
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//       $$$$$                                                                                                                                                          
//       $:::$                                                                                                                                                          
//   $$$$$:::$$$$$$ FFFFFFFFFFFFFFFFFFFFFF      AAA         TTTTTTTTTTTTTTTTTTTTTTTEEEEEEEEEEEEEEEEEEEEEE                                                               
// $$::::::::::::::$F::::::::::::::::::::F     A:::A        T:::::::::::::::::::::TE::::::::::::::::::::E                                                               
//$:::::$$$$$$$::::$F::::::::::::::::::::F    A:::::A       T:::::::::::::::::::::TE::::::::::::::::::::E                                                               
//$::::$       $$$$$FF::::::FFFFFFFFF::::F   A:::::::A      T:::::TT:::::::TT:::::TEE::::::EEEEEEEEE::::E                                                               
//$::::$              F:::::F       FFFFFF  A:::::::::A     TTTTTT  T:::::T  TTTTTT  E:::::E       EEEEEE                                                               
//$::::$              F:::::F              A:::::A:::::A            T:::::T          E:::::E                                                                            
//$:::::$$$$$$$$$     F::::::FFFFFFFFFF   A:::::A A:::::A           T:::::T          E::::::EEEEEEEEEE                                                                  
// $$::::::::::::$$   F:::::::::::::::F  A:::::A   A:::::A          T:::::T          E:::::::::::::::E                                                                  
//   $$$$$$$$$:::::$  F:::::::::::::::F A:::::A     A:::::A         T:::::T          E:::::::::::::::E                                                                  
//            $::::$  F::::::FFFFFFFFFFA:::::AAAAAAAAA:::::A        T:::::T          E::::::EEEEEEEEEE                                                                  
//            $::::$  F:::::F         A:::::::::::::::::::::A       T:::::T          E:::::E                                                                            
//$$$$$       $::::$  F:::::F        A:::::AAAAAAAAAAAAA:::::A      T:::::T          E:::::E       EEEEEE                                                               
//$::::$$$$$$$:::::$FF:::::::FF     A:::::A             A:::::A   TT:::::::TT      EE::::::EEEEEEEE:::::E                                                               
//$::::::::::::::$$ F::::::::FF    A:::::A               A:::::A  T:::::::::T      E::::::::::::::::::::E                                                               
// $$$$$$:::$$$$$   F::::::::FF   A:::::A                 A:::::A T:::::::::T      E::::::::::::::::::::E                                                               
//      $:::$       FFFFFFFFFFF  AAAAAAA                   AAAAAAATTTTTTTTTTT      EEEEEEEEEEEEEEEEEEEEEE                                                               
//      $$$$$        

pragma solidity ^0.8.7;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract F8TOKEN is ERC20, Ownable {
    constructor() ERC20("F8 Token", "FATE"){}

    /// turn on/off contributions
    bool public allowContributions;

    /// a minimum contribution to participate in the seed round
    uint256 public constant MIN_CONTRIBUTION = .1 ether;

    /// limit the maximum contribution for each wallet
    uint256 public constant MAX_CONTRIBUTION = .5 ether;

    /// the maximum amount of eth that this contract will accept for seed round
    uint256 public constant HARD_CAP = 65 ether;

    /// total number of tokens available
    uint256 public constant MAX_SUPPLY = 8_888_000_000_000 * 10**18;

    /// 46% of tokens reserved for seed round
    uint256 public constant SEED_SUPPLY = 4_088_480_000_000 * 10**18;

    /// 54% of tokens reserved for LP, social airdrops, and team mint
    uint256 public constant RESERVE_MAX_SUPPLY = 4_799_520_000_000 * 10**18;

    /// used to track the total contributions for the seed round
    uint256 public TOTAL_CONTRIBUTED;

    /// used to track the total number of contributors
    uint256 public NUMBER_OF_CONTRIBUTORS;

    /// a struct used to keep track of each contributors address and contribution amount
    struct Contribution {
        address addr;
        uint256 amount;
    }

    /// mapping of contributions
    mapping (uint256 => Contribution) public contribution;

    /// index of an address to it's contribition information
    mapping (address => uint256) public contributor;


 mapping(address => bool) public whitelist;

    /**
     * @notice Add to whitelist
     */
    function addToWhitelist(address[] calldata toAddAddresses) 
    external onlyOwner
    {
        for (uint i = 0; i < toAddAddresses.length; i++) {
            whitelist[toAddAddresses[i]] = true;
        }
    }

    /// collect seed round contributions
    function sendToSeed() public payable {

    require(whitelist[msg.sender], "NOT_IN_WHITELIST");

        /// look up the sender's current contribution amount in the mapping
        uint256 currentContribution = contribution[contributor[msg.sender]].amount;

        /// initialize a contribution index so we can keep track of this address' contributions
        uint256 contributionIndex;

        require(msg.value >= MIN_CONTRIBUTION, "Contribution too low");

        /// check to see if contributions are allowed
        require (allowContributions, "Contributions not allowed");

        /// enforce per-wallet contribution limit
        require (msg.value + currentContribution <= MAX_CONTRIBUTION, "Contribution exceeds per wallet limit");

        /// enforce hard cap
        require (msg.value + TOTAL_CONTRIBUTED <= HARD_CAP, "Contribution exceeds hard cap"); 

        if (contributor[msg.sender] != 0){
            /// no need to increase the number of contributors since this person already added
            contributionIndex = contributor[msg.sender];
        } else {
            /// keep track of each new contributor with a unique index
            contributionIndex = NUMBER_OF_CONTRIBUTORS + 1;
            NUMBER_OF_CONTRIBUTORS++;
        }

        /// add the contribution to the amount contributed
        TOTAL_CONTRIBUTED = TOTAL_CONTRIBUTED + msg.value;

        /// keep track of the address' contributions so far
        contributor[msg.sender] = contributionIndex;
        contribution[contributionIndex].addr = msg.sender;
        contribution[contributionIndex].amount += msg.value;
    }

        /// allow contributors to send directly to the contract
    receive() external payable {
        sendToSeed();
    }

    function airdropSeed() external onlyOwner {
        
        /// determine the price per token
        uint256 pricePerToken = (TOTAL_CONTRIBUTED * 10 ** 18)/SEED_SUPPLY;

        /// loop over each contribution and distribute tokens
        for (uint256 i = 1; i <= NUMBER_OF_CONTRIBUTORS; i++) {

            /// convert contribution to 18 decimals
            uint256 contributionAmount = contribution[i].amount * 10 ** 18;

            /// calculate the percentage of the pool based on the address' contribution
            uint256 numberOfTokensToMint = contributionAmount/pricePerToken;

            /// mint the tokens to the address
            _mint(contribution[i].addr, numberOfTokensToMint);
        }
    }

    /// team mint the remainder of the pool to round out the supply
    function teamMint() external onlyOwner {

        /// calculate the remaining supply
        uint256 numberToMint = MAX_SUPPLY - totalSupply();
        
        /// don't allow the team mint until the tokens have been airdropped
        require (numberToMint <= RESERVE_MAX_SUPPLY, "Team mint limited to reserve max");

        /// mint the remaining supply to the team's wallet
        _mint(msg.sender, numberToMint);
    }

     /// set whether or not the contract allows contributions
    function setAllowContributions(bool _value) external onlyOwner {
        allowContributions = _value;
    }

    /// if there are not enough contributions or we hit a bug, refund everyone their ETH
    function refundContributors(uint256 _startIndex, uint256 _endIndex) external onlyOwner {
        for (uint256 i = _startIndex; i <= _endIndex;) {
            payable(contribution[i].addr).transfer(contribution[i].amount);
            ++i;
        }
    }

    /// allows the owner to withdraw the funds in this contract
    function withdrawBalance(address payable _address) external onlyOwner {
        (bool success, ) = _address.call{value: address(this).balance}("");
        require(success, "Withdraw failed");
    }
}
// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../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() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @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");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: @openzeppelin/contracts/token/ERC20/ERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/ERC20.sol)

pragma solidity ^0.8.0;

import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5.05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless this function is
     * overridden;
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
            // decrementing then incrementing.
            _balances[to] += amount;
        }

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        unchecked {
            // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
            _balances[account] += amount;
        }
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
            // Overflow not possible: amount <= accountBalance <= totalSupply.
            _totalSupply -= amount;
        }

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

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;
    }
}

// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);
}