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"content": "// SPDX-License-Identifier: MIT\n// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)\n\npragma solidity ^0.8.1;\n\n/**\n * @dev Collection of functions related to the address type\n */\nlibrary Address {\n /**\n * @dev Returns true if `account` is a contract.\n *\n * [IMPORTANT]\n * ====\n * It is unsafe to assume that an address for which this function returns\n * false is an externally-owned account (EOA) and not a contract.\n *\n * Among others, `isContract` will return false for the following\n * types of addresses:\n *\n * - an externally-owned account\n * - a contract in construction\n * - an address where a contract will be created\n * - an address where a contract lived, but was destroyed\n * ====\n *\n * [IMPORTANT]\n * ====\n * You shouldn't rely on `isContract` to protect against flash loan attacks!\n *\n * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets\n * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract\n * constructor.\n * ====\n */\n function isContract(address account) internal view returns (bool) {\n // This method relies on extcodesize/address.code.length, which returns 0\n // for contracts in construction, since the code is only stored at the end\n // of the constructor execution.\n\n return account.code.length > 0;\n }\n\n /**\n * @dev Replacement for Solidity's `transfer`: sends `amount` wei to\n * `recipient`, forwarding all available gas and reverting on errors.\n *\n * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost\n * of certain opcodes, possibly making contracts go over the 2300 gas limit\n * imposed by `transfer`, making them unable to receive funds via\n * `transfer`. {sendValue} removes this limitation.\n *\n * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].\n *\n * IMPORTANT: because control is transferred to `recipient`, care must be\n * taken to not create reentrancy vulnerabilities. Consider using\n * {ReentrancyGuard} or the\n * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].\n */\n function sendValue(address payable recipient, uint256 amount) internal {\n require(address(this).balance >= amount, \"Address: insufficient balance\");\n\n (bool success, ) = recipient.call{value: amount}(\"\");\n require(success, \"Address: unable to send value, recipient may have reverted\");\n }\n\n /**\n * @dev Performs a Solidity function call using a low level `call`. A\n * plain `call` is an unsafe replacement for a function call: use this\n * function instead.\n *\n * If `target` reverts with a revert reason, it is bubbled up by this\n * function (like regular Solidity function calls).\n *\n * Returns the raw returned data. To convert to the expected return value,\n * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].\n *\n * Requirements:\n *\n * - `target` must be a contract.\n * - calling `target` with `data` must not revert.\n *\n * _Available since v3.1._\n */\n function functionCall(address target, bytes memory data) internal returns (bytes memory) {\n return functionCallWithValue(target, data, 0, \"Address: low-level call failed\");\n }\n\n /**\n * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with\n * `errorMessage` as a fallback revert reason when `target` reverts.\n *\n * _Available since v3.1._\n */\n function functionCall(\n address target,\n bytes memory data,\n string memory errorMessage\n ) internal returns (bytes memory) {\n return functionCallWithValue(target, data, 0, errorMessage);\n }\n\n /**\n * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n * but also transferring `value` wei to `target`.\n *\n * Requirements:\n *\n * - the calling contract must have an ETH balance of at least `value`.\n * - the called Solidity function must be `payable`.\n *\n * _Available since v3.1._\n */\n function functionCallWithValue(\n address target,\n bytes memory data,\n uint256 value\n ) internal returns (bytes memory) {\n return functionCallWithValue(target, data, value, \"Address: low-level call with value failed\");\n }\n\n /**\n * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but\n * with `errorMessage` as a fallback revert reason when `target` reverts.\n *\n * _Available since v3.1._\n */\n function functionCallWithValue(\n address target,\n bytes memory data,\n uint256 value,\n string memory errorMessage\n ) internal returns (bytes memory) {\n require(address(this).balance >= value, \"Address: insufficient balance for call\");\n (bool success, bytes memory returndata) = target.call{value: value}(data);\n return verifyCallResultFromTarget(target, success, returndata, errorMessage);\n }\n\n /**\n * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n * but performing a static call.\n *\n * _Available since v3.3._\n */\n function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {\n return functionStaticCall(target, data, \"Address: low-level static call failed\");\n }\n\n /**\n * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],\n * but performing a static call.\n *\n * _Available since v3.3._\n */\n function functionStaticCall(\n address target,\n bytes memory data,\n string memory errorMessage\n ) internal view returns (bytes memory) {\n (bool success, bytes memory returndata) = target.staticcall(data);\n return verifyCallResultFromTarget(target, success, returndata, errorMessage);\n }\n\n /**\n * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n * but performing a delegate call.\n *\n * _Available since v3.4._\n */\n function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {\n return functionDelegateCall(target, data, \"Address: low-level delegate call failed\");\n }\n\n /**\n * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],\n * but performing a delegate call.\n *\n * _Available since v3.4._\n */\n function functionDelegateCall(\n address target,\n bytes memory data,\n string memory errorMessage\n ) internal returns (bytes memory) {\n (bool success, bytes memory returndata) = target.delegatecall(data);\n return verifyCallResultFromTarget(target, success, returndata, errorMessage);\n }\n\n /**\n * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling\n * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.\n *\n * _Available since v4.8._\n */\n function verifyCallResultFromTarget(\n address target,\n bool success,\n bytes memory returndata,\n string memory errorMessage\n ) internal view returns (bytes memory) {\n if (success) {\n if (returndata.length == 0) {\n // only check isContract if the call was successful and the return data is empty\n // otherwise we already know that it was a contract\n require(isContract(target), \"Address: call to non-contract\");\n }\n return returndata;\n } else {\n _revert(returndata, errorMessage);\n }\n }\n\n /**\n * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the\n * revert reason or using the provided one.\n *\n * _Available since v4.3._\n */\n function verifyCallResult(\n bool success,\n bytes memory returndata,\n string memory errorMessage\n ) internal pure returns (bytes memory) {\n if (success) {\n return returndata;\n } else {\n _revert(returndata, errorMessage);\n }\n }\n\n function _revert(bytes memory returndata, string memory errorMessage) private pure {\n // Look for revert reason and bubble it up if present\n if (returndata.length > 0) {\n // The easiest way to bubble the revert reason is using memory via assembly\n /// @solidity memory-safe-assembly\n assembly {\n let returndata_size := mload(returndata)\n revert(add(32, returndata), returndata_size)\n }\n } else {\n revert(errorMessage);\n }\n }\n}\n"
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