code: def __call__(self, a):
      if isinstance(a, DATAFRAME_TYPE):
          self.output_types = [OutputType.dataframe]
          return self._call_dataframe(a)
      else:
          self.output_types = [OutputType.series]
          return self._call_series(a)
  
file_path: mars/mars/dataframe/sort/sort_index.py
imports: import pandas
  from ...None import opcodes
  from ...core import OutputType, recursive_tile
  from ...serialization.serializables import ListField, BoolField
  from ...tensor.base.sort import _validate_sort_psrs_kinds
  from ...utils import calc_nsplits
  from ..utils import parse_index, validate_axis, build_concatenated_rows_frame, standardize_range_index
  from ..operands import DATAFRAME_TYPE
  from .core import DataFrameSortOperand
  from .psrs import DataFramePSRSOperandMixin, execute_sort_index
label_desc: Use image node_id 5 for calling the DataFrameSortIndex obj's underlying member method code with example usage: obj.__call__(a) and returns: self, self