1_bar
2#No effect, just hint for the user:
3#“Hey, this isn’t really meant to be a part of the public interface
4#of this class.
5#Best to leave it alone.”
6__bar
7#protects the variable from getting overridden in subclasses
8__bar__
9#It’s best to stay away from using names that start and
10#end with double underscores (“dunders”) in your own programs
11#to avoid collisions with future changes to the Python language.
12#reserved for magic methods