code: def teardown_method(self) -> None:
      self.freezer.stop()
      clear_db_dags()
      clear_db_datasets()
  
imports: from __future__ import annotations
  import pytest
  import time_machine
  from airflow.api_connexion.schemas.dataset_schema import DatasetCollection, DatasetEventCollection, dataset_collection_schema, dataset_event_collection_schema, dataset_event_schema, dataset_schema
  from airflow.datasets import Dataset
  from airflow.models.dataset import DatasetEvent, DatasetModel
  from airflow.operators.empty import EmptyOperator
  from tests.test_utils.db import clear_db_dags, clear_db_datasets
label_desc: Use image node_id 2 for calling the TestDatasetSchemaBase obj's underlying member method code with example usage: obj.teardown_method() without return types