Traversing graphs

[Vlad Dumitrescu]

From: "Vladimir Sekissov" <svg@REDACTED>
> May be it could be easier with continuation-passing style

Yes, that's a good idea. I will look at it.

Maybe my main problem is that I try to wite a general mapfold-like function,
when it would be easier to do it in several steps. For example first mark
some nodes with attributes, then transform the graph according to the
markings.

Thanks again!
/Vlad