Playing recursively with trees

This is not a book about programming on Python as the topic is vast. Having said that, it's not common for introductory Python books to discuss recursive programming at length. Recursive programming techniques are usually well tailored to deal with trees. They are also a common programming strategy with functional programming dialects, which can be quite useful when you perform concurrent development, which you can perform when processing very large datasets.

The phylogenetic notion of a tree is slightly different from computer science. Phylogenetic trees can be rooted (then they are normal tree data structures) or unrooted, making them undirected acyclic graphs. Phylogenetic trees can also have weights in their edges. Thus, be mindful of this when you read the documentation; if text is written by a phylogeneticist, you can expect the tree (rooted and unrooted), while most other documents will use undirected acyclic graphs for unrooted trees. Having said that...