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);
    //         }
    //     }
    // }
}
/**
 * @dev Collection of functions related to the address type
 */
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 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
 * ====
 */