library AddressUtil
{
    using AddressUtil for *;

    function isContract(
        address addr
        )
        internal
        view
        returns (bool)
    {
        uint32 size;
        assembly { size := extcodesize(addr) }
        return (size > 0);
    }

    function toPayable(
        address addr
        )
        internal
        pure
        returns (address payable)
    {
        return address(uint160(addr));
    }

    // Works like address.send but with a customizable gas limit
    // Make sure your code is safe for reentrancy when using this function!
    function sendETH(
        address to,
        uint    amount,
        uint    gasLimit
        )
        internal
        returns (bool success)
    {
        if (amount == 0) {
            return true;
        }
        address payable recipient = to.toPayable();
        /* solium-disable-next-line */
        (success, ) = recipient.call{value: amount, gas: gasLimit}("");
    }

    // Works like address.transfer but with a customizable gas limit
    // Make sure your code is safe for reentrancy when using this function!
    function sendETHAndVerify(
        address to,
        uint    amount,
        uint    gasLimit
        )
        internal
        returns (bool success)
    {
        success = to.sendETH(amount, gasLimit);
        require(success, "TRANSFER_FAILURE");
    }
}
/// @title Utility Functions for addresses
/// @author Daniel Wang - <daniel@loopring.org>
/// @author Brecht Devos - <brecht@loopring.org>
function sendETHAndVerify(
        address to,
        uint    amount,
        uint    gasLimit
        )
        internal
        returns (bool success)
    {
        success = to.sendETH(amount, gasLimit);
        require(success, "TRANSFER_FAILURE");
    }
// Works like address.transfer but with a customizable gas limit
// Make sure your code is safe for reentrancy when using this function!