[BerislavLopac]

> lists aren’t immutable when passed to another function

Well, lists are never immutable in Python; you want to use tuples for that.

[macintux]

True, what I really want is referential transparency, not immutability per se.

I’ve only used tuples in Python as a small data structure, will have to experiment with using them as a list substitute, thanks.

[BerislavLopac]

Just keep in mind that a tuple's elements can still be mutable, so it's not a "frozen" data structure throughout.