Python - The meaning of a single- and a double-underscore before an object name
Today I am going to explain the difference between single- and a double-underscore before an object name
Variables in a class with a leading underscore are simply to indicate to other programmers that the variable should be private. However, nothing special is done with the variable itself.
Double Underscore (Name Mangling)
From the Python docs
And a warning from the same page: