You can define class variables multiple ways in Python, but they also work differently. Underscore is used for "private" or "protected" variables, altough there are no such definitions in Python....
Python is an interpreted, general-purpose high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive. Its use of indentation for block delimiters is unique among popular programming languages.