function vestedAmount() public view returns (uint256) {
        uint256 vested = 0;

        for (uint256 i = 0; i < vesting_offsets.length; i = i.add(1)) {
            if (block.timestamp > start.add(vesting_offsets[i])) {
                vested = vested.add(vesting_amounts[i]);
            }
        }

        return vested;
    }