Python class polymorphism explication with example

This is a very simple example of Python polymorphism with the purpose 
to shade some light in how this is working.

Description:

I defined 2 parent classes ParentA, ParentB each having defined a method
named method_xx. The class ParentA have an additional method named method_a
I defined a class named Child(ParentA, ParentB) which inherit ParentA, ParentB 
with a method named method_a which overwrite the ParentA method_a
I made an instance of Child(ParentA, ParentB) named my_child_class_instance
Using my_child_class_instance I will acces:
        -   method_a from class Child
        -   method_a from class ParentA
        -   method_xx from class ParentA
        -   method_xx from class ParentB

Running:

class_polymorphism.py

Credits:

Alin Rizea
https://www.linkedin.com/in/alin-rizea-b10368104/