underline in Python

double underline for both head and tail

__foo__ ๐Ÿ—๐Ÿ—๐Ÿ—๐Ÿ—

Defines a special method, usually a system-defined name, like __init__().

Single underline

_foo ๐Ÿ—

A single-underline begins with a protected variable, which means that the protected type can only be accessed by itself and not by from module import *

double underline

__foo ๐Ÿ—๐Ÿ—

Double underline represent private type variables, allowing only the class itself to access