Python - strictly private instance attributes

Question

As per my (limited) Python knowledge, obj.__n = 3 can't modify instance attribute since it's strictly private. But, why doesn't this instruction raise any error or warning?

class Myclass:
def __init__(self, n=1):
self.__n = n
def val_n(self):
return self.__n
obj = Myclass(2)
obj.__n = 3
print(obj.val_n())

Answer 1

Right here -> obj.__n = 3
The name __n is mangled so you'll always get an attribute error.

Fix it like so:
obj._Myclass__n = 3