code: def test_empty_lineage_backend(self):
      backend = get_backend()
      assert backend is None
  
imports: from __future__ import annotations
  from unittest import mock
  import attr
  import pytest
  from airflow.lineage import AUTO, apply_lineage, get_backend, prepare_lineage
  from airflow.lineage.backend import LineageBackend
  from airflow.lineage.entities import File
  from airflow.models import TaskInstance
  from airflow.operators.empty import EmptyOperator
  from airflow.utils import timezone
  from airflow.utils.context import Context
  from airflow.utils.types import DagRunType
  from tests.test_utils.config import conf_vars
label_desc: Use image node_id 5 for calling the TestLineage obj's underlying member method code with example usage: obj.test_empty_lineage_backend() without return types