I am having some problems making a class interface in processing. By which I mean, the kind of interface which gets implemented by classes:

http://download.oracle.com/docs/cd/E17409_01/javase/tutorial/java/IandI/index.html

This is possible in processing, right? Are there some examples floating around of how to do this? 

I'm getting error messages when I even try adding an interface block into the code (either something about "unexpected token: interface" or "the nested type XXXX cannot hide an enclosing type"). I think someone pointing me to an example that works will be enough for me to figure it out.

Thanks,

Gabe