Membership operators

• The membership operators in returns True if the left operand matches the value of some element in a container

sizes = [3, 5, 7, 9.5, 10, 10.5, 11]
if 10 in sizes:
  print('Sizes include size 10')

Sizes include size 10

It can also be used to check whether a substring is part of a larger string:

data = '123abc456'
if 'abc' in data:
  print('abc found in data')

abc found in data