1. Class names should follow the UpperCaseCamelCase convention,
  2. Functions, variables and attributes should be all lowercase and sparated by an underscore (a.ka. snake_case),
  3. Non-public/protected attributes should begin with a single underscore,
  4. Use double underscore for private attributes.
class MyPythonClass:

  def regular_attribute(self):
    print("Hello Python!")

  def _protected_attribute(self):
    print("Hello Python!")

  def __private_attribute(self):
    print("Hello Python!")

For more info: PEP 8 – Style Guide for Python Code

All done!