Exercise:

From the HW2 extra for experts problem, we know that it is possible to
perform recursion using the y-combinator.  For example, the following
expresses the factorial procedure, invoked with the argument 3.

   ((let ((f (lambda (fun x)
               (if (> x 1)
                   (* x (fun fun (- x 1)))
                   1)) ))
      (lambda (n) (f f n)) )
    3)

Draw the environment resulting from the above expression.