how to check if something is not in a list in python code example

Example 1: how to check if value is in list python

>>> letters = [a,b,c,d,e]
>>> 'a' in letters:
True

Example 2: python not in list

>>> 3 not in [2, 3, 4]
False
>>> 3 not in [4, 5, 6]
True