Ask HN: Best database for tree storage and traversal?

The gist of what I'm trying to do is have a tree, traverse through every possible branch until all leaf nodes have been visited.

I need to also be able to modify any node along a branch. I originally thought about using MySQL but it seems really complicated. So I turn to graph databases.

I want a python example which does this but can't find it in the docs for Neo4j, OrientDB, ArangoDB