demo_python_ref_keyword_assert_2.py:
​x
 
x = "hello"
​
#if condition returns False, AssertionError is raised:
assert x == "goodbye", "x should be 'hello'"
​
C:\Users\My Name>python demo_python_ref_keyword_assert_2.py
Traceback (most recent call last):
  File "demo_python_ref_keyword_assert_2.py", line 4, in <module>
    assert x == "goodbye", "x should be 'hello'"
AssertionError: x should be 'hello'