Membership (in, not in)

With strings, the membership operator determined whether a single character is a member of a string. With lists (and tuples), we can check whether an object is a member of a list (or tuple).

Example

>>> mixup_list = ["one","two","three","four"]
>>> "one" in mixup_list
True
>>> 'two' in mixup_list
True
>>> "nine" not in mixup_list
True