contract PostDeliveryCrowdsale is TimedCrowdsale {
    using SafeMath for uint256;

    mapping(address => uint256) private _balances;
    __unstable__TokenVault private _vault;

    constructor() public {
        _vault = new __unstable__TokenVault();
    }

    /**
     * @dev Withdraw tokens only after crowdsale ends.
     * @param beneficiary Whose tokens will be withdrawn.
     */
    function withdrawTokens(address beneficiary) public {
        require(hasClosed(), "PostDeliveryCrowdsale: not closed");
        uint256 amount = _balances[beneficiary];
        require(amount > 0, "PostDeliveryCrowdsale: beneficiary is not due any tokens");

        _balances[beneficiary] = 0;
        _vault.transfer(token(), beneficiary, amount);
    }

    /**
     * @return the balance of an account.
     */
    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev Overrides parent by storing due balances, and delivering tokens to the vault instead of the end user. This
     * ensures that the tokens will be available by the time they are withdrawn (which may not be the case if
     * `_deliverTokens` was called later).
     * @param beneficiary Token purchaser
     * @param tokenAmount Amount of tokens purchased
     */
    function _processPurchase(address beneficiary, uint256 tokenAmount) internal {
        _balances[beneficiary] = _balances[beneficiary].add(tokenAmount);
        _deliverTokens(address(_vault), tokenAmount);
    }
}
/**
 * @title PostDeliveryCrowdsale
 * @dev Crowdsale that locks tokens from withdrawal until it ends.
 */
function _processPurchase(address beneficiary, uint256 tokenAmount) internal {
        _balances[beneficiary] = _balances[beneficiary].add(tokenAmount);
        _deliverTokens(address(_vault), tokenAmount);
    }
/**
 * @dev Overrides parent by storing due balances, and delivering tokens to the vault instead of the end user. This
 * ensures that the tokens will be available by the time they are withdrawn (which may not be the case if
 * `_deliverTokens` was called later).
 * @param beneficiary Token purchaser
 * @param tokenAmount Amount of tokens purchased
 */