Before the new AST module was added, I wrote http://dalkescientific.com/Python/python4ply-tutorial.html http://dalkescientific.com/Python/python4ply-tutorial.ht

Before the new AST module was added, I wrote http://dalkescientific.com/Python/python4ply-tutorial.html http://dalkescientific.com/Python/python4ply-tutorial.html , http://www.dalkescientific.com/writings/diary/archive/2006/08/30/gardensnake_language.html http://www.dalkescientific.com/writings/diary/archive/2006/0..., and http://www.dalkescientific.com/writings/diary/archive/2010/02/22/instrumenting_the_ast.html http://www.dalkescientific.com/writings/diary/archive/2010/0... . Those seem like something you're looking for.