(if (string=? head "")
	      (if (null? tail)
		  result
		  (loop (car tail)(cdr tail) result))
	      (let* ((key (substring head 0 2))
		     (rem (substring head 2 (string-length head)))
		     (num (string->number key 16))
		     (ch  (if (and (number? num)
                                   (exact? num))
			      (integer->char num)
			      #f)) ;; this is an error. I will probably regret this some day
		     (chstr  (if ch (make-string 1 ch) ""))
		     (newres (if ch
				 (string-append result chstr rem)
				 (string-append result head))))
		;; (print "head: " head " num: " num " ch: |" ch "| chstr: " chstr)