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"""

Python doesn't have private and protected attributes. It follows the convention

that attributes prefixed with a _ are considered an implementation detail.

However, nothing prevents you from accessing it even tho you shouldn't

access it because it can change in the next update.

With this in mind, guess the output of the following piece of code.

"""

next_uid = 1

class User:

def __init__(self, name):

global next_uid

self.name = name

self.__id = next_uid

next_uid += 1

u = User("john")

print(f"name={u.name}, id={u.__id}")

"""

The output is an AttributeError: 'User' object has no attribute '__id'

When you use __id, it will block all subclasses of the User class from

using their own __id attribute. Therefore, Python provides something

called 'name mangling' (it is also used in C, Java and other languages).

"""

print(vars(u)) # {'name': 'john', '_User__id': 1}

"""

Within the User class you can access __id but from the outside, the

attribute is changed to _User__id freeing up names classes can use for

nonpublic attributes

"""