An API reference file is a python file that describes one or more classes using doc strings. It should briefly describe the classes. If there is only one class in the file, this doc string is probably not needed. This doc string describes the class. It should include introductory and background information.
Doc strings are in structured text format.
The class doc string should also describe attributes like so. Note that the 'self' argument is not listed in the method signature. The format of an API reference file is quite similar to a normal Python module. It consists of class and function definitions including signatures and doc strings. Doc strings are interpreted at structured text.