AST assignment due Monday

As we decided in class, the AST-building assignment will be due Monday.

The requirement is very simple:  Parse Cool programs, and print the tree in any way you like.   Dot (GraphViz) is one very nice way to look at trees, but if you use it I suggest you find a way to look at just parts of the overall AST, because graphic depictions of large trees get unreadable fast.  While a nice indented listing is also good, I wouldn't invest a huge amount of time building a tree pretty-printer unless you think you will have other uses for it later.