Grab- given byte of engineering data

(defun john-convert ()
  "Takes Hex dump from Wireshark, looks for the ack offset \"3032\"
   Then finds the byte offset requested, and converts that hex to binary"
  (interactive)
  (beginning-of-line)
  (search-forward "3032")
  (newline)
  (while (not (eolp))
    (forward-char 2)(princ " " (current-buffer)))
  (beginning-of-line)
  (setq byte-offset (read-from-minibuffer "Byte: "))
  (forward-word (string-to-number byte-offset))
  (princ "\n" (current-buffer))
  (forward-word)
  (forward-char)
  (princ "\n" (current-buffer))
  (previous-line)
  (beginning-of-line)
  (princ (concat  ";;byte " byte-offset ": 0x") (current-buffer))
  (delete-char 1)
  (forward-char)
  ;; do python processing on (current-word)
  (forward-word)
  (setq beg (point))
  (convert-to-binary)
  (kill-region beg (point))
  (princ " -> " (current-buffer))
  (yank) (backward-delete-char 1)
  (backward-char 4) (princ " " (current-buffer)))

(defun convert-to-binary ()
  (interactive)
  (call-process "python" nil (current-buffer) nil "-c"
                   (format "print bin(int(%s))[2:].zfill(8)" (current-word))))

called out from elisp to python to do the binary conversion.