problem with "hiding" object

[league55]

Here is the instantiation:

cipher = Cipher()

And here's the error message:

Output:
Traceback (most recent call last):
  File "C:\Users\leagu\pythonprojects\costcontrol\classes\keyclass.py", line 25, in <module>
    cipher = Cipher(data)
  File "C:\Users\leagu\pythonprojects\costcontrol\classes\keyclass.py", line 7, in __init__
    self.cipher = value
  File "C:\Users\leagu\pythonprojects\costcontrol\classes\keyclass.py", line 15, in cipher
    if self.cipher != None:
  File "C:\Users\leagu\pythonprojects\costcontrol\classes\keyclass.py", line 11, in cipher
    return self.__cipher
AttributeError: 'Cipher' object has no attribute '_Cipher__cipher'