You need to create a class User that has the following attributes:
active — a boolean attribute that indicates whether a user is active at the moment,
n_active — the number of active users,
user_name — string with the username,
users — a list of all users.
The catch is that some of these attributes should be defined as class attributes, and others should be instance attributes.
If there are 2 or more instance attributes, please list them in the __init__ in alphabetical order.
NOTE: you do NOT need to create an instance of this class or print anything. You are also NOT required to write any additional code for modifying class attributes (leave them with default values).
