function determineReward(uint _challengeID) public view returns (uint) {
        require(!challenges[_challengeID].resolved && voting.pollEnded(_challengeID));

        
        if (voting.getTotalNumberOfTokensForWinningOption(_challengeID) == 0) {
            return challenges[_challengeID].stake.mul(2);
        }

        return (challenges[_challengeID].stake).mul(2).sub(challenges[_challengeID].rewardPool);
    }