anchor.diff:    (format t "    -i|--input FILE    Input filename~%")
     (format t "    -o|--output FILE   Output filename~%")
     (format t "    -c|--columns NUM   Number of columns to print (default=8)~%")
  -  #+sbcl (sb-ext:quit :unix-status 0))
  +  #+sbcl (sb-ext:exit :code 0))
   
   (defun main ()
     (let ((argv #+sbcl sb-ext:*posix-argv*))
  
positive.code:        do (write-row
  	   (subseq input-sequence i (min (+ i num-columns) num-bytes))
  	   output-stream
  	   (>= (+ i num-columns) num-bytes)))))
  
  (defun interactive-main (argv command-line-args)
    (multiple-value-bind (args options errors) (getopt:getopt argv command-line-args)
      ;(format t "args=~A~%options=~A~%errors=~A~%" args options errors)
      (let ((input-filename (get-option-value "input" options))
  	  (output-filename (get-option-value "output" options))
  
negative.code: 	(with-open-file (output-stream output-filename :direction :output :if-exists :supersede)
  	  (write-c-array (read-stream-into-array input-stream) output-stream num-columns)))))
    t)
  
  (defun print-usage-and-exit (program-name)
    (format t "usage: ~A --input=FILE --output=FILE [--columns=NUM]~%" program-name)
  