function withdrawTokens() public {
        uint tokensToSend = 0;
        for (uint i = 0; i < allocatedIndex[msg.sender].length; i++) {
            uint releaseDate = allocatedIndex[msg.sender][i];
            if (releaseDate <= now) {
                Balance storage b = allocated[msg.sender][releaseDate];
                tokensToSend += b.tokens;
                b.tokens = 0;
            }
        }

        if (tokensToSend > 0) {
            allocatedTokens -= tokensToSend;
            if (!token.issue(msg.sender, tokensToSend)) {
                revert();
            }
        }
    }