contract FinalizableCrowdsale is Crowdsale, Ownable {
    using SafeMath for uint256;

    bool public isFinalized = false;

    event Finalized();
 
    constructor(address _owner) public Ownable(_owner) {}

    /**
    * @dev Must be called after crowdsale ends, to do some extra finalization
    * work. Calls the contract's finalization function.
    */
    function finalize() onlyOwner public {
        require(!isFinalized);
        require(hasEnded());

        finalization();
        emit Finalized();

        isFinalized = true;
    }

    /**
    * @dev Can be overridden to add finalization logic. The overriding function
    * should call super.finalization() to ensure the chain of finalization is
    * executed entirely.
    */
    function finalization() internal {}
}
/**
 * @title FinalizableCrowdsale
 * @dev Extension of Crowdsale where an owner can do extra work
 * after finishing.
 */
function finalization() internal {}
/**
 * @dev Can be overridden to add finalization logic. The overriding function
 * should call super.finalization() to ensure the chain of finalization is
 * executed entirely.
 */