Subgraphs

Hey folks, really cool library! I was wondering if its possible to have subgraphs. If I had two graphs of two kinds with different hashes, I'd like to connect them somehow.

Hi! At the time, something like that doesn't exist.

There will be functions for merging and connecting graphs of the same type. Subgraphs of different types sound interesting - I haven't thought about that yet, but it makes sense.