(<a href='#write-octet'>write-octet</a> #xF0 compressor)
  (write-octet #x0D compressor)
  (write-octet #x00 compressor)
  (write-octet #xD1 compressor))

(defmethod <a href='#process-input'>process-input</a> :after ((compressor foo-compressor) input start count)
  (declare (ignore input start))
  (incf (data-length compressor) count))

(defmethod <a href='#finish-data-format'>finish-data-format</a> :after ((compressor foo-compressor))
  (let ((length (data-length compressor)))
    (write-octet (ldb (byte 8