Composition:

When an instance of a class contains another class.
Composition is a "has a" relationship.
A bookclub "has a " member.
A class Bookclub could have an attribute that is self.members, which could be made up of instances of the class Member.
This allows a class to use the attributes& methods of a class, or multiple classes, within its own defintion.
The composite class has a (or multiple) component class(es)

Magic Methods (aka Special Methods)

__init__ is a special method.
Some other ones to include are __repr__ and __str__ .
If we use dunder str (aka __str__) within our class definition, we are re-writing the rules for what we want Python to do when we call str() for an object of that class. We are also re-writing the rules for what to print when we print(object). Instead of giving us something like <object class ......09090-9-0999-> it will give us the more useful info we asked it to print.
Note: if __repr__ is defined, and __str__ is not, the object will behave as though __str__=__repr__
__repr__ is more for the developers. It's goal is to be unambigious.
- In general, it is helpful to return something that can be used to recreate the object, aka ClassName(argument1, argument2, argument3)
__str__ is more for the end users... a readable version