code: def hook(self):
      return PubSubAsyncHook()
  
imports: from __future__ import annotations
  from unittest import mock
  from uuid import UUID
  import httplib2
  import pytest
  from google.api_core.exceptions import AlreadyExists, GoogleAPICallError
  from google.api_core.gapic_v1.method import DEFAULT
  from google.cloud.exceptions import NotFound
  from google.cloud.pubsub_v1.types import ReceivedMessage
  from googleapiclient.errors import HttpError
  from airflow.providers.google.cloud.hooks.pubsub import PubSubAsyncHook, PubSubException, PubSubHook
  from airflow.providers.google.common.consts import CLIENT_INFO
  from airflow.version import version
label_desc: Use image node_id 1 for calling the TestPubSubAsyncHook obj's underlying member method code with example usage: obj.hook() and returns: PubSubAsyncHook