> - isolated within a module This only exists in fairy land. In practice, mixing code from different versions is always the root of subtle bugs and ABI/API mes

> - isolated within a module This only exists in fairy land. In practice, mixing code from different versions is always the root of subtle bugs and ABI/API mess. For me in front of a big chunk of legacy code, I'd rather wrap them in a separate process and communicate with the remaining part through RPCs if possible.