Python's private variable starts with dunder(double under) and not ends with dunder.

private_var.py

class Spam:

  def __init__(self):
    self._var = "I'm under var"
    self.__dunder_var = "I'm double under var"

  def get_var(self):
    return self._var

  def get_dunder_var(self):
    return self.__dunder_var

if __name__ == '__main__':
  spam = Spam()
  print('---- access to _var direct')
  print(spam._var)
  print('---')
  print('---- access to __dunder_var direct')
  try:
    print(spam.__dunder_var)
  except AttributeError:
    print('AttributeError is raised when access to __dunder_var direct')
  print('---')
  print('---- access to _var using accessor')
  print(spam.get_var())
  print('---')
  print('---- access to __dunder_var using accessor')
  print(spam.get_dunder_var())
  print('---')

"""
---- access to _var direct
I'm under var
---
---- access to __dunder_var direct
AttributeError is raised when access to __dunder_var direct
---
---- access to _var using accessor
I'm under var
---
---- access to __dunder_var using accessor
I'm double under var
---

>>> # just renamed from the outside, it doesn't mean it's inaccessible.
>>> spam.__dunder_var
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Spam' object has no attribute '__dunder_var'
>>> spam._Spam__dunder_var
"I'm double under var"
"""