code: def _infer_df_func_returns(
      self,
      in_groupby,
      in_df,
      dtypes=None,
      dtype=None,
      name=None,
      index=None,
  ):
      index_value, output_type, new_dtypes = None, None, None
  
      if self.output_types is not None and (
          dtypes is not None or dtype is not None
      ):
          ret_dtypes = dtypes if dtypes is not None else (dtype, name)
          ret_index_value = (
              parse_index(index) if index is not None else None
          )
          return ret_dtypes, ret_index_value
  
      try:
          infer_df = in_groupby.op.build_mock_groupby().apply(
              self.func, *self.args, **self.kwds
          )
  
          if len(infer_df) <= 2:
              # we create mock df with 4 rows, 2 groups
              # if return df has 2 rows, we assume that
              # it's an aggregation operation
              self.maybe_agg = True
  
          # todo return proper index when sort=True is implemented
          index_value = parse_index(
              infer_df.index[:0], in_df.key, self.func
          )
  
          # for backward compatibility
          dtype = dtype if dtype is not None else dtypes
          if isinstance(infer_df, pd.DataFrame):
              output_type = output_type or OutputType.dataframe
              new_dtypes = new_dtypes or infer_df.dtypes
          elif isinstance(infer_df, pd.Series):
              output_type = output_type or OutputType.series
              new_dtypes = new_dtypes or (
                  name or infer_df.name,
                  dtype or infer_df.dtype,
              )
          else:
              output_type = OutputType.series
              new_dtypes = (name, dtype or pd.Series(infer_df).dtype)
      except:  # noqa: E722  # nosec
          pass
  
      self.output_types = (
          [output_type] if not self.output_types else self.output_types
      )
      dtypes = new_dtypes if dtypes is None else dtypes
      index_value = index_value if index is None else parse_index(index)
      return dtypes, index_value
  
imports: import numpy
  import pandas
  from ...None import opcodes
  from ...core import OutputType
  from ...core.context import get_context
  from ...core.custom_log import redirect_custom_log
  from ...serialization.serializables import AnyField, BoolField, TupleField, DictField, FunctionField, StringField
  from ...core.operand import OperatorLogicKeyGeneratorMixin
  from ...utils import enter_current_session, quiet_stdio, get_func_token, tokenize
  from ..operands import DataFrameOperandMixin, DataFrameOperand
  from ..utils import auto_merge_chunks, build_empty_df, build_empty_series, parse_index, validate_output_types, make_dtypes, make_dtype, clean_up_func, restore_func
label_desc: Use image node_id 5 for calling the GroupByApply obj's underlying member method code with example usage: obj._infer_df_func_returns(in_groupby, in_df, dtypes, dtype, name, index) and returns: dtypes,  index_value, ret_dtypes,  ret_index_value