;Chapter 4, Bryan Test 3, Page 63-66

(deftest test-sequences-adv ()
  (check
    (equal (elt '(a b c d e) 2) 'c) ;elt returns the element at zero based index x.
    
    (equal (format nil "~A" (elt "ABCDE" 2)) "C") ; converts the element to a string, and compares
    (equal (position #\n "Bryan Lemon") 4); finds the first instance of n in name
    (equal (position #\n "Bryan Lemon" :start 5) 10); finds the instance of n that is after the 5th character.
    (equal (position #\n "Bryan Lemon" :from-end t) 10) ; finds the last instance of n. Return value is indexed from the start not the end.
    (equal (remove-duplicates "Bryan Lemon") "Brya Lemon"))) ;Removes all duplicate letters, preserving the last.