Inheritance & super()

Why this matters

Django's class-based views, DRF serializers, and SQLAlchemy's declarative base all lean on multiple inheritance and cooperative super() calls. Understanding the C3 linearization MRO is what separates engineers who can debug a diamond-shaped mixin stack from those who cargo-cult super().__init__() and pray.

Common pitfalls

• Forgetting **kwargs in cooperative __init__ — every mixin in a chain must forward unknown args or the MRO breaks silently.
• Calling Parent.__init__(self) instead of super().__init__() — this skips siblings in the MRO and defeats mixin composition.
• Assuming left-to-right resolution — read Cls.__mro__ before debugging; C3 is subtler than it looks.