code: def import_rl_strategy_without_tianshou():
      from nni.nas.strategy import PolicyBasedRL
  
      with pytest.raises(ImportError, match="tianshou"):
          PolicyBasedRL()
  
file_path: nni/test/ut/nas/test_optional_dependency.py
imports: import argparse
  import subprocess
  import sys
  import pytest
label_desc: Use image node_id 2 for calling a global function with example usage: import_rl_strategy_without_tianshou() without return types