Programming project 2 is due 7/20 at 11:59 PM. It consists of all the exercises 
in Section 2.2.4 of the text. You can't actually draw anything until you finish the 
project! To begin, copy the file ~cs61a/lib/picture.scm to your directory. To draw 
pictures, once you've completed the exercises: 
> (cs) 
> (ht) 
> (name-of-your-painter-here full-frame) 

For example: 
> (wave full-frame) 
> ((square-limit wave 3) full-frame)