PEP 8 is a famous style guide for Python code. It's not enforced by the interpreter but you are highly discouraged to ignore it. There is a tool to automatically check whether your code is following PEP 8 recommendations. Its former name is pep8, but it was renamed to pycodestyle at the request of Guido. Now you should use pycodestyle installed with pip intall pycodestyle only. You can check whether pycodestyle is happy with your project like this: $ pycodestyle . -qq --statistics 1 E302 expected 2 blank lines, found 1 1 E305 expected 2 blank lines after class or function definition, found 1 20 E501 line too long (83 > 79 characters)