Support of non tree structures

Hi! Thanks for the library!
Could someone tell, does the library work only with tree structures or it also supports non tree graphs like here?
https://en.wikipedia.org/wiki/Tree_(data_structure)#/media/File:Directed_graph_with_branching_SVG.svg
I mean structures with more than one root and multi parent nodes.

No source files or tests are named. Start by reviewing the library's graph functionality for ActiveRecord and compare its behavior with the linked directed-graph example, including multiple roots and multi-parent nodes. Done means the supported graph structures are established and the issue's support question is answered or scoped into a concrete change.

Written by the indexing model from the issue text.