docstr: Tests if ConnectorPipeline.__getitem__() works as intended.
code: def test_pipeline_indexing(self):
      """Tests if ConnectorPipeline.__getitem__() works as intended."""
      context = ConnectorContext(
          {}, observation_space=gym.spaces.Box(-1, 1, (1,))
      )
      some_connector = MeanStdObservationFilterAgentConnector(context)
      some_other_connector = ObsPreprocessorConnector(context)
      # Create a dummy pipeline just for indexing purposes
      pipeline = ConnectorPipeline(
          context, [some_connector, some_other_connector]
      )
  
      for key, expected_value in [
          (MeanStdObservationFilterAgentConnector, [some_connector]),
          ("MeanStdObservationFilterAgentConnector", [some_connector]),
          (SyncedFilterAgentConnector, [some_connector]),
          ("SyncedFilterAgentConnector", []),
          (ClipRewardAgentConnector, []),
          ("can i get something?", []),
          (0, [some_connector]),
          (1, [some_other_connector]),
      ]:
          self.assertEqual(pipeline[key], expected_value)
  
file_path: ray/rllib/connectors/tests/test_connector.py
imports: import unittest
  import gymnasium
  from ray.rllib.connectors.connector import Connector, ConnectorPipeline
  from ray.rllib.connectors.connector import ConnectorContext
  from ray.rllib.connectors.agent.synced_filter import SyncedFilterAgentConnector
  from ray.rllib.connectors.agent.mean_std_filter import MeanStdObservationFilterAgentConnector
  from ray.rllib.connectors.agent.obs_preproc import ObsPreprocessorConnector
  from ray.rllib.connectors.agent.clip_reward import ClipRewardAgentConnector
label_desc: Use image node_id 2 for calling the TestConnectorPipeline obj's underlying member method code with example usage: obj.test_pipeline_indexing() without return types