Question

Here is a snippet of code from django.core.exceptions:

class MiddlewareNotUsed(Exception):
    "This middleware is not used in this server configuration"
    pass

Is the bare string in the body of the class a mere literal for documentation ? Or does it perform some magic ?

Answer 1

It’s a doc string:

A docstring is 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.