docs: def header(self):
          """Return the frame header (as an array of bytes)."""
          total_length = self.total_length()
          res = [0x06, 0x10, 0, 0, 0, 0]
          res[2] = (self.service_type_id >> 8) & 0xff
          res[3] = (self.service_type_id >> 0) & 0xff
          res[4] = (total_length >> 8) & 0xff
          res[5] = (total_length >> 0) & 0xff
          return res