    constructor(address _marketplace, address _aggregator, bytes32 _marketplaceCodeHash, bytes32 _aggregatorCodeHash) {
        if (_marketplace == address(0) || _aggregator == address(0) || 
            _marketplace.codehash != _marketplaceCodeHash || _aggregator.codehash != _aggregatorCodeHash) {
            revert InvalidAddress();
        }     
        marketplace = ILooksRareExchange(_marketplace);
        aggregator = _aggregator;
    }
