code: def resolver_function(
      *,
      output_type: Optional[_TypeHint] = None,
      unwrap_dict_key: Optional[Union[str, Sequence[str]]] = None,
  ) -> Callable[..., ResolverFunction]:
      ...
  
imports: import contextlib
  import inspect
  from typing import Callable, Type, Union, Mapping, Any, Optional, Sequence, cast, overload
  from tfx.dsl.control_flow import for_each_internal
  from tfx.dsl.input_resolution import resolver_op
  from tfx.types import artifact
  from tfx.types import channel
  from tfx.types import resolved_channel
  from tfx.utils import doc_controls
  from tfx.utils import typing_utils
label_desc: Use image node_id 3 for calling a global function with example usage: resolver_function() without return types