function addAuction(uint40 _startTime, uint40 _duration, uint128 _startPrice, uint40 _cutieId) public onlyOperator
    {
        require(coreContract.getApproved(_cutieId) == address(this) || coreContract.ownerOf(_cutieId) == address(this));
        auctions.push(Auction(_startPrice, address(0), _startTime + _duration, 0, _startTime, _cutieId));
    }