library AddressUtils {

    /**
     * @dev Returns whether the target address is a contract.
     * @param _addr Address to check.
     */
    function isContract(
        address _addr
    )
    internal
    view
    returns (bool)
    {
        uint256 size;

        /**
         * XXX Currently there is no better way to check if there is a contract in an address than to
         * check the size of the code at that address.
         * See https://ethereum.stackexchange.com/a/14016/36603 for more details about how this works.
         * TODO: Check this again before the Serenity release, because all addresses will be
         * contracts then.
         */
        assembly { size := extcodesize(_addr) } // solium-disable-line security/no-inline-assembly
        return size > 0;
    }

}
/**
 * @dev Utility library of inline functions on addresses.
 */
function isContract(
        address _addr
    )
    internal
    view
    returns (bool)
    {
        uint256 size;

        /**
         * XXX Currently there is no better way to check if there is a contract in an address than to
         * check the size of the code at that address.
         * See https://ethereum.stackexchange.com/a/14016/36603 for more details about how this works.
         * TODO: Check this again before the Serenity release, because all addresses will be
         * contracts then.
         */
        assembly { size := extcodesize(_addr) } // solium-disable-line security/no-inline-assembly
        return size > 0;
    }
/**
 * @dev Returns whether the target address is a contract.
 * @param _addr Address to check.
 */