(VAR f x xs )
(RULES 
        app(app(map,f),nil) -> nil
        app(app(map,f),app(app(cons,x),xs)) -> app(app(cons,app(f,x)),app(app(map,f),xs))
        app(app(treemap,f),app(app(node,x),xs)) -> app(app(node,app(f,x)),app(app(map,app(treemap,f)),xs))
        
)