What is Optional[] used for?

Question

Python

It is not clear why and how Optional[] is used.
In the example below, I'm setting a variable of type Optional[Point]. I expected that when assigning a value to a variable of a different type, a run-time error will fly out, but no. Quietly assigned to both 5 and "hello". What's the point of using Optional then? Or am I doing something wrong?

from typing import Optional

class Point:
    def __init__(self,val):
        self.x = val

    def __str__(self):
        return str(self.x)


a : Optional[Point]
b : Optional[Point]
c : Optional[Point]


a = None      # 
b = 5             #здесь должна быть ошибка ??
c = Point(22)
a = "hello"     #здесь должна быть ошибка ??

Answer 1

Type annotations are indifferent to the interpreter. We can say that these are just strict comments that linters can react to, and that's it.