Write a recursive Racket function "keep-short-rec" that takes an integer and a list of strings as parameters and evaluates to a list of strings. The resulting list should be all of the strings from the original list, maintaining their relative order, whose string length is less than the integer parameter. For example, (keep-short-rec 3 '("abc" "ab" "a")) should evaluate to '("ab" "a") because these are the only strings shorter than 3.