Emit a message to a single client, a room, or all the clients
        connected to the namespace.

        Note: this method is a coroutine.

async def emit(self, event, data, namespace, room=None, skip_sid=None,
                   callback=None, **kwargs):
        """Emit a message to a single client, a room, or all the clients
        connected to the namespace.

        Note: this method is a coroutine.
        """
        if namespace not in self.rooms or room not in self.rooms[namespace]:
            return
        tasks = []
        for sid in self.get_participants(namespace, room):
            if sid != skip_sid:
                if callback is not None:
                    id = self._generate_ack_id(sid, namespace, callback)
                else:
                    id = None
                tasks.append(self.server._emit_internal(sid, event, data,
                                                        namespace, id))
        if tasks == []:  # pragma: no cover
            return
        await asyncio.wait(tasks)