code: def get_all_users(self) -> Optional[str]:
      return cast(Optional[str], self._mts._match_call("get_all_users"))
  
imports: import contextlib
  import os
  from typing import Any, Iterator, List, Optional, cast
  import responses
  from responses import registries
  import determined
  from determined.common.api import authentication
label_desc: Use image node_id 3 for calling the MockTokenStoreInstance obj's underlying member method code with example usage: obj.get_all_users() and returns: cast