As per 4.7.7. Documentation Strings: Here are some conventions about the content and formatting of documentation strings. The first line should always be a short, concise summary of the object’s purpose. For brevity, it should not explicitly state the object’s name or type, since these are available by other means (except if the name happens to be a verb describing a function’s operation). This line should begin with a capital letter and *end with a period*. The below code is missing *end with a period *in the docstring. Bug? URL: https://docs.python.org/3/tutorial/classes.html#class-objects class MyClass: """A simple example class""" i = 12345 def f(self): return 'hello world'