> immutable and mutable data

I don't get how this is an example of python mixing up mutable/immutable data, and I'm unaware of a situation where python does. Conceptually I'm not even sure what you mean by a language 'mixing up mutable and immutable data' unless it's literally just a buggy/non hardened implementation.

A = (1, ); A[0] = 2 # this raises an exception