How to use the asgiref.sync function in asgiref

def unsubscribe_sync(cls, *, group=None):
        """Unsubscribe, synchronous version."""
        # Send the message to the Channels group.
        group = cls._group_name(group)
        group_send = asgiref.sync.async_to_sync(cls._channel_layer().group_send)
        group_send(group=group, message={"type": "unsubscribe", "group": group})

def broadcast_sync(cls, *, group=None, payload=None):
        """Broadcast, synchronous version."""
        # Manually serialize the `payload` to allow transfer of Django
        # models inside the `payload`.
        serialized_payload = Serializer.serialize(payload)

        # Send the message to the Channels group.
        group = cls._group_name(group)
        group_send = asgiref.sync.async_to_sync(cls._channel_layer().group_send)
        group_send(
            group=group,
            message={
                "type": "broadcast",
                "group": group,
                "payload": serialized_payload,
            },

# confirmation message is sent before any subscription
                # notifications.
                if self.confirm_subscriptions:
                    await self._send_gql_data(
                        operation_id,
                        data=self.subscription_confirmation_message["data"],
                        errors=self.subscription_confirmation_message["errors"],
                    )

                # Subscribe to the observable.
                # NOTE: The function `on_next` is called from a
                # threadpool which processes all GraphQL requests. So we
                # wrap `_send_gql_data` into `async_to_sync` here, so
                # eventually `_send_gql_data` will be invoked from the
                # current eventloop.
                send_gql_data = asgiref.sync.async_to_sync(self._send_gql_data)
                result.subscribe(
                    lambda r: send_gql_data(operation_id, r.data, r.errors)
                )

            else:
                # Respond to a query or mutation immediately.

                # If Graphene complains that the request is invalid
                # (e.g. query contains syntax error), then the `data`
                # argument is `None` and the 'errors' argument contains
                # all errors that occurred before or during execution.
                # The `result` is an instance of the `ExecutionResult`.
                await self._send_gql_data(operation_id, result.data, result.errors)
                # Tell the client that the request processing is over.
                await self._send_gql_complete(operation_id)

async def _get_user(self):
        user = None

        try:
            if self.scope['jwt']:
                user = await sync.sync_to_async(passive_credentials_auth)(self.scope['jwt'])
        except (APIException, InvalidTokenError):
            # Can ignore JWT auth failures, scope['user'] will not be set.
            pass

        return user

query = payload["query"]
            op_name = payload.get("operationName")
            variables = payload.get("variables", {})

            # Create object-like context (like in `Query` or `Mutation`)
            # from the dict-like one provided by the Channels.
            context = ScopeAsContext(self.scope)

            # The `register` will be called from the worker thread
            # (spawned for a GraphQL processing) when a client
            # subscribes. So we "synchronize" it with `async_to_sync`.
            # NOTE: It is important to invoke `async_to_sync` in the
            # thread with the eventloop which serves this consumer. This
            # assures that IO operations is performed within a single
            # eventloop.
            register_subscription = asgiref.sync.async_to_sync(
                functools.partial(self._register_subscription, operation_id)
            )

            def register_middleware(next_middleware, root, info, *args, **kwds):
                """Transfers registration function to the `_subscribe`.

                Check that `next_middleware` is precisely a subscription
                handler `Subscription._subscribe` and hack it's `root`
                to deliver the subscription registration function.
                """
                from .subscription import Subscription

                # We do not expose `Subscription._subscribe` because
                # `Subscription` is a public interface class. So it OK
                # to get `Subscription._subscribe` here - we are tightly
                # coupled anyway.

def mutate(self, info, username, password):
        """Login request."""

        # Ask Django to authenticate user.
        user = django.contrib.auth.authenticate(username=username, password=password)
        if user is None:
            return Login(ok=False)

        # Use Channels to login, in other words to put proper data to
        # the session stored in the scope. The `info.context` is
        # practically just a wrapper around Channel `self.scope`, but
        # the `login` method requires dict, so use `_asdict`.
        asgiref.sync.async_to_sync(channels.auth.login)(info.context._asdict(), user)
        # Save the session, `channels.auth.login` does not do this.
        info.context.session.save()

        return Login(ok=True)