function addRoundPrice(uint _startTime,uint _endTime, uint _price, address[] _whitelist) public onlyOperator {
        if (_whitelist.length == 0) {
            roundPrices.push(FundingRound(_startTime, _endTime,_price,false));
        } else {
            for (uint i=0 ; i < _whitelist.length ; i++ ) {
                whitelist[roundPrices.length][_whitelist[i]] = true;
            }
            roundPrices.push(FundingRound(_startTime, _endTime,_price,true));
        }
    }