Iteration through tree

How can I use the iteration mechanism to iterate through a tree?
Is CURSOR_TREE_ITERATOR the right class?
The following does not compile because iterator expects the type
CURSOR_TREE [BINARY_SEARCH_TREE [INTEGER_32]].

class
   APPLICATION

create
   make

feature -- Initialization
   make is
       -- Run application.
     local
       tree: BINARY_SEARCH_TREE [INTEGER]
       iterator: CURSOR_TREE_ITERATOR BINARY_SEARCH_TREE [INTEGER]]
     do
       create tree.make (500)
       tree.put (400)
       tree.put (600)
       create iterator
       iterator.set (tree)
     end
end -- class APPLICATION


There must be a simple solution without requiring the client programmer 
to build his own class inheriting from the deferred class CURSOR_TREE, 
isn't it?



Thx