code: def unpack_message(buffer):
      
      hdr_size = Header().get_size()
      hdr_buff, msg_buff = buffer[:hdr_size], buffer[hdr_size:]
      header = Header()
      header.unpack(hdr_buff)
      message = new_message_from_header(header)
      message.unpack(msg_buff)
      return message
docs: Unpack the whole buffer, including header pack.
  
      Args:
          buffer (bytes): Bytes representation of a openflow message.
  
      Returns:
          object: Instance of openflow message.