| 1 minute, 55 seconds | Name binding, Recursion, Iteration, and Continuations - slide 22 : 42 | 
(define (string-merge str-list-1 str-list-2)
 (cond ((null? str-list-1) (apply string-append str-list-2))
       ((null? str-list-2) (apply string-append str-list-1))
       (else (string-append
              (car str-list-1) (car str-list-2)
              (string-merge (cdr str-list-1) (cdr str-list-2)))))) An application of string-merge which converts a list of strings to a string with a given separator.  | 
 A tail recursive version of string-merge.  | 

