What is the proper way to comment functions in Python?

The correct way to do it is to provide a docstring. That way, help(add) will also spit out your comment.

def add(self):
    """Create a new user.

    Line 2 of comment...
    And so on... 
    """

That's three double quotes to open the comment and another three double quotes to end it. You can also use any valid Python string. It doesn't need to be multiline and double quotes can be replaced by single quotes.

See: PEP 257

Use a docstring, as others have already written.

You can even go one step further and add a doctest to your docstring, making automated testing of your functions a snap.

Use a docstring:

A string literal that occurs as the first statement in a module, function, class, or method definition. Such a docstring becomes the __doc__ special attribute of that object.

All modules should normally have docstrings, and all functions and classes exported by a module should also have docstrings. Public methods (including the __init__ constructor) should also have docstrings. A package may be documented in the module docstring of the __init__.py file in the package directory.

String literals occurring elsewhere in Python code may also act as documentation. They are not recognized by the Python bytecode compiler and are not accessible as runtime object attributes (i.e. not assigned to __doc__ ), but two types of extra docstrings may be extracted by software tools:

1. String literals occurring immediately after a simple assignment at the top level of a module, class, or __init__ method are called "attribute docstrings".
2. String literals occurring immediately after another docstring are called "additional docstrings".

Please see PEP 258 , "Docutils Design Specification" [2] , for a detailed description of attribute and additional docstrings...

The principles of good commenting are fairly subjective, but here are some guidelines:

• Function comments should describe the intent of a function, not the implementation
• Outline any assumptions that your function makes with regards to system state. If it uses any global variables (tsk, tsk), list those.
• Watch out for excessive ASCII art. Having long strings of hashes may seem to make the comments easier to read, but they can be annoying to deal with when comments change
• Take advantage of language features that provide 'auto documentation', i.e., docstrings in Python, POD in Perl, and Javadoc in Java