# How to Think Like a Computer Scientist: The PreTeXt Interactive Edition

## Section10.5List Membership

in and not in are boolean operators that test membership in a sequence. We used them previously with strings and they also work here.

### Checkpoint10.5.1.

What is printed by the following statements?
alist = [3, 67, "cat", [56, 57, "dog"], [ ], 3.14, False]
print(3.14 in alist)

• True
• Yes, 3.14 is an item in the list alist.
• False
• There are 7 items in the list, 3.14 is one of them.

### Checkpoint10.5.2.

What is printed by the following statements?
alist = [3, 67, "cat", [56, 57, "dog"], [ ], 3.14, False]
print(57 in alist)

• True
• in returns True for top level items only. 57 is in a sublist.
• False
• Yes, 57 is not a top level item in alist. It is in a sublist.