function _createUnicorn(address _owner) private returns(uint256) {
        require(gen0Count < gen0Limit);
        uint256 newUnicornId = unicornToken.createUnicorn(_owner);
        
        blackBox.createGen0.value(unicornManagement.oraclizeFee())(newUnicornId);
        emit CreateUnicorn(_owner, newUnicornId, 0, 0);
        gen0Count = gen0Count.add(1);
        return newUnicornId;
    }