What does it mean to put a dot in a Python class argument?
Question: In Python, I saw a class definition as the following:

    
    
    from protorpc import messages
    
    # Create the request string containing the user's name
    class HelloRequest(messages.Message):
        my_name = messages.StringField(1, required=True)
    

What does `messages.Message` mean?


Answer: 
    from protorpc import messages
    class HelloRequest(messages.Message):
    

Is just another way of spelling:

    
    
    from protorpc.messages import Message
    class HelloRequest(Message):
    

Or even...

    
    
    import protorpc
    class HelloRequest(protorpc.messages.Message):
    

That is, `HelloRequest` derives from the `Message` `class` in the `messages`
_submodule_ of the `protorpc`
[package](http://docs.python.org/2/tutorial/modules.html#packages).

