We’d better start with the hardest question: “What is functional programming (FP), anyway?”

One answer would be to say that functional programming is what you do when you program in languages like Lisp, Scheme, Clojure, Scala, Haskell, ML, OCAML, Erlang, or a few others. That is a safe answer, but not one that clarifies very much. Unfortunately, it is hard to get a consistent opinion on just what functional programming is, even from functional programmers themselves. A story about elephants and blind men seems apropos here. It is also safe to contrast functional programming with “imperative programming” (what you do in languages like C, Pascal, C++, Java, Perl, Awk, TCL, and most others, at least for the most part). Functional programming is also not object-oriented programming (OOP), although some languages are both. And it is not Logic Programming (e.g., Prolog), but again some languages are multiparadigm.

Python is most definitely not a “pure functional programming language”; side effects are widespread in most Python programs. That is, variables are frequently rebound, mutable data collections often change contents, and I/O is freely interleaved with computation. It is also not even a “functional programming language” more generally. However, Python is a multiparadigm language that makes functional programming easy to do when desired, and easy to mix with other programming styles.