how to write not in python code example

Example 1: is not in python

li = [1,2,'a','b']
if 'hello' not in li:
    print('hello is not in the list')

Example 2: not in python

x = 10
if not x:
    print("True")
else:
    print("False")

Example 3: not equal python

if a != b:
	pass
if not a == b:
	pass