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Exercise 2.1
The append function **

The function append, which is a standard Scheme function, concatenates two or more lists. Let us here show a version which appends two lists:

  (define (my-append lst1 lst2)
       (cond ((null? lst1) lst2)
             (else (cons (car lst1) (my-append (cdr lst1) lst2)))))

We will now challenge ourselves by programming an iterative solution, by means of tail recursion. We start with the standard setup:

  (define (my-next-append lst1 lst2)
    (my-next-append-1 lst1 lst2 ...))

where my-next-append-1 is going to be the tail recursive function:

  (define (my-next-append-1 lst1 lst2 res)
    (cond ((null? lst1) ...)
          (else (my-next-append-1 (cdr lst1) lst2 ...))))

Fill out the details, and try out your solution.

You may encounter a couple of problems! Do your best to work around these problems, maybe by changing aspects of the templates I have given above.

Solution