Playing recursively with trees

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

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