A Concise Introduction to Programming in Python

Chapter 17

Mutable and Immutable Objects

Over the last few chapters, you may have noticed some strange or confusing

things about strings and lists. The two types are very similar, but there are

significant differences that first appeared when we listed their methods.

Look again at the list of operations in the section “Lists Are Not Like Strings”

and at the note below the methods that modify lists on page 78:

These methods all modify the list they are called on, and only

.pop() returns anything.

Compare that with the note below the methods that seem like they should

modify strings on page 95:

None of these methods changes the original string; they modify ...