Python parameter behavior

Question

My understanding of function parameters in Python is that they are like empty objects until function call and that's it. eg.

def square(x): #where x is an empty var defined here.
    return x*x #for the scope of this function

So how does this work, where "NamedTuple" is a callback function I assume? Does "NamedTuple" return value gets used as the parameter to class Car()?

>>> from typing import NamedTuple

>>> class Car(NamedTuple):
...     color: str
...     mileage: float
...     automatic: bool

>>> car1 = Car("red", 3812.4, True)

>>> # Instances have a nice repr:
>>> car1
Car(color='red', mileage=3812.4, automatic=True)

Answer 1

class Car(NamedTuple): is a class declaration, not a function call. NamedTuple is a class that Car is derived from.

Answer 2

No, NamedTuple is not a function, but a class. This is called inheritance (or subclassing), more about it here.