generic graph (data structure) functions in Emacs?

[Ted Zlatanov]

Does Emacs have generic graph building and traversing libraries?  I
couldn't find anything.

I need these specifically for a n-child tree structure, which is easy
to do with nested lists, but I would prefer to use graph-oriented
algorithms.  I thought I'd check here before writing my own.

The reason is that the Gnus assistants need to lay out each assistant
screen as a graph node, with next/previous bidirectional edges between
them.  Right now, a simply n-child tree is enough, but I would like to
allow for the possibility of circular paths and multiple parents in
the assistant, which could be useful in the future.

Thanks
Ted