In Python, in and not in operators are called membership operators. Their purpose is to check if an object is a member of a certain sequence object like string, list, or tuple. The not in operator returns false if object is present in sequence, true if not found
>>> 'p' not in 'Tutorialspoint' False >>> 'c' not in 'Tutorialspoint' True >>> 10 not in range(0,5)