9. Membership operations

Membership operators are used to test if a sequence is presented in an object.

9.1. Membership operations

Membership operators are useful to determine the presence of an element in a sequence, such as a string or list.

Operator	Evaluates to ``True`` if:		Example
in	A variable value is in a sequence		x in [1, 2, 3, 4]
not in	A variable value is not in a sequence		x not in [1, 2, 3, 4]

Example of membership operation in strings:

a = 'o'
b = 'John'
print(f'{a} in {b} is {a in b}')          # o in John is True
print(f'{a} not in {b} is {a not in b}')  # o not in John is False

Example of membership operation in lists:

x = 7
value_list = [1, 2, 3, 4]

print(x in value_list)
print(x not in value_list)