(defun IndexOf(base_string search_string)
	(if (or (string= search_string "") (string= base_string ""))
 	    -1
	    (IndexOf1 base_string search_string 0)
        )
  )
    
  (defun IndexOf1(base_string search_string pos)
	(if (> pos (1- (length base_string)))
	    -1
	    (if (string= (substring base_string pos
				    (+ pos (length search_string)))
			 search_string)
	        pos
	        (IndexOf1 base_string search_string (1+ pos))
	    )
	)
  )

  (defun Reverse(s)
        (Reverse1 s "")
  )

  (defun Reverse1(s rs)
	(if (string= s "")
	    rs
	    (Reverse1 (substring s 0 (1- (length s)))
		      (concat rs (substring s (1- (length s)) (length s))))
	)
  )