#What is the essence of Python nested classes?.
It means that the properties of one class point to another class.
Class A:
Class B:
Pass.
Equivalent to:
Class B:
Pass.
Class A:
B= B.
#Question 1: Who is the parent class of the internal class?.
Based on question 0, anyone can have a parent class, it definitely won't be an external class A Because when using nested writing for B, A does not yet exist.
#Question 2: If the external class is not instantiated, can the internal class be instantiated?.
Understanding problem 0, so it is possible.
#Question 3: Can internal classes access the properties of external classes?.
The definition clause of B cannot access A because A is currently being defined and does not exist yet. It can be accessed in the method because when calling the method, A exists.