Assuming that you have the code listed below:

(define (foo list1 list2)
  (cond
    ((null? list1) list2)
    (else 
       (cons (car list1) 
             (foo (cdr list1) list2)   
       ) 
     )
   )
)

What would be the result when evaluating the following expression?

(foo '(4 5 6) '(a b c))