Classes and objects

A class defines a type. __init__ runs when you create an instance and stores its state on self; methods are functions that take self as the first parameter.

__repr__ decides how the object prints, which makes debugging far easier. Other dunder methods let your objects work with len(), ==, sorting and iteration.

Reach for a class when data and behaviour travel together. A plain dict or function is often the better answer for one-off transformations.