// File: contracts/Cx3.sol




// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/// @title: cowDAO Cowmunnity Cowllection
/// @author: manifold.xyz

import "./ERC721Creator.sol";

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//                                                                                                                                     //
//                                                                                                                                     //
//    kkkkkOkOOOOOO0OO000000000000000000000000000000000000000000KK0000KK00000000KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK0000000OOOOOkkkxxxx    //
//    OOOOO00O0000000000000000000000000000000KKKKK00KKKKKKKK000KKKKKKKKKK0KKKKKKKKKKKKKKKKKKKKKKKKXXKKKKKKKKKKKKKKKKKK0000000OOOOOO    //
//    OOO0000000000000000000000000000KKK000KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKXXXXXXXXXXXXXXXXXXXXXKKKKKKKK00000000    //
//    0000KKKKK000KKKKKKKK0000OOOO00000KK00000KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKXXXXKXXXXXXXXXXXXXXXXXXXXXXXKKKKKKKKKKKK0    //
//    0KKKKKKKK0000KKKKK00Okxxxxkkkxxk000000000K000KKKKKKKKKKKKKKKKKKK00000KKKKKKKKKKKKKKKXXXKKXXXXXXXXXXXXXXXXXXXXXXXXXXKKKKKKKKKK    //
//    0KKKKKKK00000K00000OkOOkkkOOxdddxk00000000000KKKKKKKKKKKKKKKKKKK00K00KKKKKKKKKKKKKKKXXKKKKKKXXXXXXXXXXXXXXXXXXXXXXXXXXKKKKKKK    //
//    0000KKKK0000KK0KK0KKKK00000Okxddddxxkxdoodk00KKKKKKKK0K00000000000K00KKKKKKKKKKKXXXKKKKKKKKKKKXXXXXXXXXXXXXXXXXXXKXXXXXKKKKKK    //
//    0000KKKKKKKKKKKKKK0O000OOkkkkkxdolodo,.  ..,;:;cxOOOkxxxkkkxxxxkO0KKKKKKKKKKKKKKXXXXKKKKKKKKKKXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX    //
//    0000KK00000KKKKK0OkkkOOko:;,,;:clclOO;.     .,collodooddxkkOOkkkkOKKKKKKKKKKKKKKKKKKKKKKKKKKXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX    //
//    000000000000KKKKKKKKK00OOkdl:;,.'loxXKdc:cclxkkxolloodddkOO00K0KKKKKXKKKXXXXXXKKKKKKKKKKKKKKXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX    //
//    0000000KKKKKKKKKKKKKKKK0kdlllcldOXOoxlcoxo:'','','.''',;ccloxO00KKKKKKXXXXXXXXKKKKKKKKKKKKKKXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX    //
//    KKKKKKKKKKKKKKKKKKKKKKKKOo;,'',ld0Ko,,coodolc,.,cccllllododddkOkO0KKKXKXXXXXXXXKKKKKKKKKKKKKKKKKKKXXXXXXXXXXXXXXXXXXXXXXXXXXX    //
//    KKKKKKKKKKKKKKKKKKKKKKXKKK0xl;:ox0K:'lo:..:dd,.lxllxO0000KKKKKKK00XXKXXXXXXXXXXXKKKKKKKK0KKKKKKKKKKKKKKXXXXXXXKKXXXXXXXXXXXXX    //
//    KKKKKKKKKKK00KKKKKKKKKKKK0oldxOXXXO'.;lc,;ll;.lKk. .':oxO00KKXXXXXKXKKKKKXXXXXKKKKKKKKKKKKKKKKKK000000KKXXXXXXKXXXXXXXXXXXXXX    //
//    KKK0000KK00000KKKKKKKKKK0kokKXNXXXx. ..,,'...l0Xx.     .;dO0KKKK0000xl;,,cdk000Okkxdollccc::lOKK0000Ol,;cdOKXXXKXXXXXXXXXXXXX    //
//    KKKK0000000000000000K00kodOKXXXXXX0dc'     ,kKXXKo'...,o0XNXXNNNXXk;.      ........       'lkKXXXXXX0;    .;xKKKXXXXXXXXXXXXX    //
//    KK0000000000000000OO0Ol....dXXXX0dOXNx. .,cOKXXXXX0kxOKXXXXXXNNXXXx.                    'oOXXXKOxOKXKx'     .l0KKXXXXXKKXXXXX    //
//    KKKKK0000000000000Okkc.    cKXOl,'dXNKl'l0KKKXXXXXXXXXXXXXXXXXXXXXO,                    ,xKKKXO:.'kXXXk'     .o0KKKKKKKKXXXXX    //
//    KKKKKK0000000000ko:,;,.....:xdold0K0xOOxc::,;xKXXXKkdolcokKXXXXXXXd.                     .xXXXK0kx0XXXXkc;;,;lox0KKKKKKKXXXXX    //
//    KK00K00K00000000Oo'  ':cllc;'..;lk0xx000k; .'oKXKKd.     .dKXXXXX0:                       lXXXXXKXXXXXXXKKKKKKOxk000KKKKXXXXX    //
//    0000K0000000000KK0dc,;:ldo:,'',::lO000000klo0KKKKKl.      ,OXKKXKl.                      'kXXXXXXXXXXXXXK0000OxdxO000KKXXXXXK    //
//    0000000000000KKKKKK0dodlllcccccldOKKKKKK00xokKKKKK0o;....cxKXKKXO,     ....            .cOXXXKxlokKXXXkc,'.....okk0000KKKXXKK    //
//    K000000000000K0K0KKKOxdddolldxkO0KKKKKK000kc:dO0KKKK0OxkOKXXXKKKKkollodkOOk:        .cx0XXXXX0;  .oKXKc       .x0k0000KKKKKKK    //
//    K0000000K000000KKKKKKOkkkxxOKKKKKKKKKKKK00kxl..;okKKKKKKKKKXXKKXXXXXXXXXXXX0l.      lKXXXXXXXX0ddx0XXXx.      .k0xO0000KKKKKK    //
//    000000000KKK00OxddddxO0OkOKKKKKKKKKKKK0000xxO;   .l0KKKKKKKKXXKKKXXXXXXOolodOOl:,,:dKXKKXXXklodk0KXXXXXk:.    'xKkk0000KKKKKK    //
//    00000000kdc;'',,.':ooccllldOKK0O00KK0000K0xOXd.   .dKKKKKKklc;,,,:lkKXX0dc:cOXXXXXNXkl;:oO0x'  .':kXXXXXO,    ,d00xk000KKKKKK    //
//    00000000d;'...,,,,lOOo:colcx0dloddk0K0000OxOXO,   .dKKKKKd.     .;oOXNNXNNNNXKKK000OoldkOOOko,    ,OXXXX0l'.  :kk00kO000KKKKK    //
//    000000000d:;;;::;:xKK0xlcccox:,oOkdkKK000Ox0XK:   ,xKKKXO,  .:ld00OdollooooxOOkOOkxddkO0OO0OOx:.  .xXXXXXXKo..l0OOK0kO00KKKXK    //
//    00000OkO0k:;:;:llcxKKKOkOkl;:,';xKkx0KK00O:c0Xd.;xOKXKX0:.'cdkOkdl:'',,:cox00xkkkkxkkO0OOkxOOOkl,. cKXXXX0O0x:oKKOOXKOkO0KKKK    //
//    00K0x:,,lo:;::clc;ck0o':oc,',cl:ckkxOK000Oc:OXOokXKXXXXk:o0KKKK0000000K0OOKKx;clcoldOO0OOxldOOkkxo:o0XXXXd',xxxKX0k0XKkk00KKK    //
//    0KK0d;ll;;;;;;::;;:cl;,cc::::;;;;okxk0000OxOKK0k0XXXK0kxOKKKKKKKKKKKKKOl'c0Kdlo;;:;lkOOkxxxxkkkxoodxOOkOXKkdO00KKKOx0XkdOKKKK    //
//    KKKKOl:::;;::::::::c:,;loccllccccd0xx0000Ok0KKKOOXXKo.'xKKKKKKKKKKKKOxxo:l0Kdcodo::lcclcloldkdoool;:OO;.oXNNNX0KXKKOxkkxO0000    //
//    KKKKKd'.,;::;:::::::,..;lclooooold0kdO000OOKXXKOOKXX0lo0KKKKKKKKKOoodOKkllxkookxdx0xc;;;,',do;;cxxdlkN0dkXNXNX00KKKKKOkkO0000    //
//    KKKKk:'.,;:::::::ccc:,';;;:loooold0OdO000kkKKKK00KKK0O0K0KKKKKKKKc.oKX0xllddx0KolxOdcdxxxclOkc,,lxk0KXNKKXNNNX00KXXKKK0000000    //
//    KKKkc;;;;;;;;;;;::::::;;,;:clllc:d0Odk000xkKK00O0KKKOO00KKKKKKKK0l;xK0xl;;cclOKkdkolkX0xkxkKKOc,ckKXKXNK0XNNNX0KXXKKKKK000000    //
//    KKK0o;;,,,,;;;;;;;;;;;;;;;:::c:::o0Odk000O0XKOOkOKKKkk000KKKK00Odcclxxc;;;;cdxOOxkdlx0KkxxdO0OdcxXXXXXN0KNNNNK0XXXKKKKKKKK000    //
//    KKKKx:;;;;;;;;;;;;;;;;;;;,;;:::;;oOOox000OKX0OOkOKK0kO000K00KOxl,,,,:kkdxxdoxxdooddoodOddkolxOOdkXNXXXX0KNNNXKKXKXXKKKKKKKK00    //
//    KKKKkc:::;;;;;;;;;;;;;;;;,;;;;;,,lOkld0000KK0OOO0KKOxO000OOOxl:::lc;;ccclc:,':ccclc:;cl::cdkkkOkdONNXKKKKNXNK0KKKXXXKKKKKKKK0    //
//    KKKKkc::::;;;;;;;;;;;;;;,,;,,,,,,cOkldOOO0KK0OOk0KKkx0Oxdxxxl,'';:,,'''.......'cc;:c:::;,:ldxkxdoxXNK000XXXXK0KKKKKKKKKKKKKK0    //
//    0Okkd:::;;;;;;;;;;;;;;;;,,,,,,,,':ddccdxkKXK0OOO0K0kk0OdokO0Oo:,',,;. .    ....cdc;:c:::c:;;ck0klckKkodkO0KX0O0KKKKKKKKKKKK00    //
//    c:::;;;;;;;;;;;;;;;;;;;:;,','',,,'.'',''cOKKkc:oOK0xllooc:odc'.':c;;'.... .. ..:lc;;,',;c;':loxxo;;:......,;;lOKKKKKKKKKKKK00    //
//    ::;;,,;;;;;;;;;;;;;;;;;;;,;;;;;;,'.......;l:'...',,...''''''''',:c;,,.  ... ...,cl;,;,,;;,,cc:;,,,'.         .:oooooooolllloo    //
//    :;,;,,:;;;;;;;;;;;;;;;;;,,;;;;;:;,'....      .       .',''''''',:l:,;,..,,,',,',;;,,,'','',,,,,,,'''..........',,,,,,,,,,,,,,    //
//    :;;;,,;;;;;;;;;;;;;;,,,,''''''''''''''................''''''',;;::;,,,,,,,,,,,,,,,,,,;;,,,'',;;;;,,,''''''',,,,,,,,,,,,,,,,,,    //
//    :;;,,,,,,,,,,,,,,,,''''''',,,,,,'''''''''''''....''''''',,,,'''','',,,,,,,,,,,,,,,,,,,,,,,''',,,,,,,,,,,,,,,,,,,,,,''',,,,,,,    //
//    :;;,,,,,,,,,,,,,,,,,,,''',,,;,,,,,,,,,,,''''''''''''''',,,,,,,,,,,,,,,,,,,,;;;;;,,,,'''''''''',,,,,,,,;;;;,,,,;;;;,,,,',,,,;;    //
//                                                                                                                                     //
//                                                                                                                                     //
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////


contract Cx3 is ERC721Creator {
    constructor() ERC721Creator("cowDAO Cowmunnity Cowllection", "Cx3") {}
}

// File: contracts/ERC721Creator.sol




// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/// @author: manifold.xyz

import "@openzeppelin/contracts/proxy/Proxy.sol";
import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/utils/StorageSlot.sol";

contract ERC721Creator is Proxy {
    
    constructor(string memory name, string memory symbol) {
        assert(_IMPLEMENTATION_SLOT == bytes32(uint256(keccak256("eip1967.proxy.implementation")) - 1));
        StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = 0xe4E4003afE3765Aca8149a82fc064C0b125B9e5a;
        Address.functionDelegateCall(
            0xe4E4003afE3765Aca8149a82fc064C0b125B9e5a,
            abi.encodeWithSignature("initialize(string,string)", name, symbol)
        );
    }
        
    /**
     * @dev Storage slot with the address of the current implementation.
     * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
     * validated in the constructor.
     */
    bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;

    /**
     * @dev Returns the current implementation address.
     */
     function implementation() public view returns (address) {
        return _implementation();
    }

    function _implementation() internal override view returns (address) {
        return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
    }    

}

// File: @openzeppelin/contracts/proxy/Proxy.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (proxy/Proxy.sol)

pragma solidity ^0.8.0;

/**
 * @dev This abstract contract provides a fallback function that delegates all calls to another contract using the EVM
 * instruction `delegatecall`. We refer to the second contract as the _implementation_ behind the proxy, and it has to
 * be specified by overriding the virtual {_implementation} function.
 *
 * Additionally, delegation to the implementation can be triggered manually through the {_fallback} function, or to a
 * different contract through the {_delegate} function.
 *
 * The success and return data of the delegated call will be returned back to the caller of the proxy.
 */
abstract contract Proxy {
    /**
     * @dev Delegates the current call to `implementation`.
     *
     * This function does not return to its internal call site, it will return directly to the external caller.
     */
    function _delegate(address implementation) internal virtual {
        assembly {
            // Copy msg.data. We take full control of memory in this inline assembly
            // block because it will not return to Solidity code. We overwrite the
            // Solidity scratch pad at memory position 0.
            calldatacopy(0, 0, calldatasize())

            // Call the implementation.
            // out and outsize are 0 because we don't know the size yet.
            let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)

            // Copy the returned data.
            returndatacopy(0, 0, returndatasize())

            switch result
            // delegatecall returns 0 on error.
            case 0 {
                revert(0, returndatasize())
            }
            default {
                return(0, returndatasize())
            }
        }
    }

    /**
     * @dev This is a virtual function that should be overridden so it returns the address to which the fallback function
     * and {_fallback} should delegate.
     */
    function _implementation() internal view virtual returns (address);

    /**
     * @dev Delegates the current call to the address returned by `_implementation()`.
     *
     * This function does not return to its internal call site, it will return directly to the external caller.
     */
    function _fallback() internal virtual {
        _beforeFallback();
        _delegate(_implementation());
    }

    /**
     * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if no other
     * function in the contract matches the call data.
     */
    fallback() external payable virtual {
        _fallback();
    }

    /**
     * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if call data
     * is empty.
     */
    receive() external payable virtual {
        _fallback();
    }

    /**
     * @dev Hook that is called before falling back to the implementation. Can happen as part of a manual `_fallback`
     * call, or as part of the Solidity `fallback` or `receive` functions.
     *
     * If overridden should call `super._beforeFallback()`.
     */
    function _beforeFallback() internal virtual {}
}

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



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

pragma solidity ^0.8.1;

/**
 * @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
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 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
                /// @solidity memory-safe-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

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



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

pragma solidity ^0.8.0;

/**
 * @dev Library for reading and writing primitive types to specific storage slots.
 *
 * Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
 * This library helps with reading and writing to such slots without the need for inline assembly.
 *
 * The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
 *
 * Example usage to set ERC1967 implementation slot:
 * ```
 * contract ERC1967 {
 *     bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
 *
 *     function _getImplementation() internal view returns (address) {
 *         return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
 *     }
 *
 *     function _setImplementation(address newImplementation) internal {
 *         require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
 *         StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
 *     }
 * }
 * ```
 *
 * _Available since v4.1 for `address`, `bool`, `bytes32`, and `uint256`._
 */
library StorageSlot {
    struct AddressSlot {
        address value;
    }

    struct BooleanSlot {
        bool value;
    }

    struct Bytes32Slot {
        bytes32 value;
    }

    struct Uint256Slot {
        uint256 value;
    }

    /**
     * @dev Returns an `AddressSlot` with member `value` located at `slot`.
     */
    function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `BooleanSlot` with member `value` located at `slot`.
     */
    function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `Bytes32Slot` with member `value` located at `slot`.
     */
    function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `Uint256Slot` with member `value` located at `slot`.
     */
    function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }
}