TopSort in Python?

[Paul Rubin]

Paddy <paddy3118 at googlemail.com> writes:
> When I needed one I didn't know the name. I'm curious, how did you
> know to look for the topological sort algorithm by name?

It's a well known algorithm in computer science, described in any
number of textbooks, for example probably 

   http://projects.csail.mit.edu/clrs/ 

There is also a wikipedia article:

  http://en.wikipedia.org/wiki/topological_sorting