docs: def send_message(self, id_service, content):
          """Write all messages to the stream in a thread-safe way."""
          if not content:
              return
          with self._lock:
              try:
                  message = "Message: %s to %s" % (content, id_service)
                  self.write_message(message)
                  self.stream.flush()  # flush after each message
                  return "message_id"
              except Exception:
                  if not self.fail_silently:
                      raise