The in membership operator checks if a given value is part of a collection of values. Here's an example with range() function:

>>> num = 5

# checks if num is present among the integers 3 or 4 or 5
>>> num in range(3, 6)
True

Instead of a series of == comparisons combined with the or boolean operator, you can utilize the in operator.

>>> pet = 'cat'

# instead of doing this
>>> pet == 'bat' or pet == 'cat' or pet == 'dog'
True

# use the membership operator
>>> pet in ('bat', 'cat', 'dog')
True

When applied to strings, the in operator performs substring comparison.

>>> fruit = 'mango'

>>> 'an' in fruit
True
>>> 'at' in fruit
False

To invert the membership test, use the not in operator.

>>> pet = 'parrot'

>>> pet in ('bat', 'cat', 'dog')
False
>>> pet not in ('bat', 'cat', 'dog')
True

info See docs.python: Membership test operations for documentation.