Math operation abstraction

Hi.

I have this function

```
(defun muo (func a b)
  (cond
    ((eq b 1) a)
    (t (funcall func a (muo func a (1- b))))))
```

Which I can use for obtaining the multiplication operation using the
addition. As an example:

* (muo #'+ 5 2)
10

and "muo #'+" means "use the multiplication".

Now if I want the exponentiation I have to do:

* (muo #'(lambda (a b) (muo #'+ a b)) 5 2)
25

This creates the exponentiation.

I would like to obtain the exponentiation using "(muo #'+ 5 2 2)"
instead, being the last argument ("2") the number of times the operation
is applied. In the case of exponentiation, it applies the multiplication
2 times, resulting in the exponentiation math operation.

I am hoping I am explaining this concept well enough.

Basically, "muo #'+" creates the addition twice, which is the
multiplication, and "muo #'+ a b 2" should create the multiplication
twice, which is the exponentiation. If I use "muo #'+ a b 3" it should
create the exponentiation twice, which is the exponentiation of the
exponentiation.

I need help in making this code modification. Seeing code is what I
want. If you can write the code and explain it, better.