Python and trees/graphs

Does anybody know of any good resources on handling trees and graphs in Python? So far I've read a little of a book on algorithms in C that explained some theory, and I've found this page that has some basics, but nothing very thorough.

What I really want is some decent tutorials or explanations of handling trees and graphs in Python, and in particular traversing them, so that I can begin to tackle graphing a family tree as part of a personal project I'm doing. It's quite complicated, much more so than a simple binary tree, so I'd like to be comfortable with graphs and trees before I tackle it.

Though I haven't read the Python version myself, Bruno Preiss's Data Structures and Algorithms with Object-Oriented Design Patterns for Python seems like a good place to start. I did read the Java version. It's introductory but covers what you need.

Thanks, that looks useful