$ python3 access-test.py
---------------------------------------------------------
Bob
Sue
Sue: 50
private attribute fetch, age
private attribute change, age
---------------------------------------------------------
bob
sue
sue: 50
private attribute fetch, age
private attribute change, age


$ python3 -O access-test.py    # Suppresses the four access error messages
---------------------------------------------------------
Bob
Sue
Sue: 50
---------------------------------------------------------
bob
sue
sue: 50