async def send_data(self, data, addr):
        """
        Send data to a remote host via the TURN server.
        """
        channel = self.peer_to_channel.get(addr)
        if channel is None:
            channel = self.channel_number
            self.channel_number += 1
            self.channel_to_peer[channel] = addr
            self.peer_to_channel[addr] = channel

            # bind channel
            await self.channel_bind(channel, addr)

        header = struct.pack('!HH', channel, len(data))
        self._send(header + data)
Send data to a remote host via the TURN server.