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;
// solhint-disable-next-line no-inline-assembly
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");

// solhint-disable-next-line avoid-low-level-calls, avoid-call-value
(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");

// solhint-disable-next-line avoid-low-level-calls
(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");

// solhint-disable-next-line avoid-low-level-calls
(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");

// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.delegatecall(data);
return _verifyCallResult(success, returndata, errorMessage);
}

function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private 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

// solhint-disable-next-line no-inline-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 sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");

// solhint-disable-next-line avoid-low-level-calls, avoid-call-value
(bool success, ) = recipient.call{ value: amount }("");
require(success, "Address: unable to send value, recipient may have reverted");
}

/**
 * @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].
 */