code: def index(self):
      return self._index
  
imports: import pandas
  from ...None import opcodes
  from ...core import recursive_tile
  from ...lib.filesystem import open_file, get_fs
  from ...serialization.serializables import KeyField, AnyField, StringField, ListField, BoolField, DictField
  from ...utils import has_unknown_shape
  from ..operands import DataFrameOperand, DataFrameOperandMixin
  from ..utils import parse_index
  from ..datasource.read_parquet import check_engine
label_desc: Use image node_id 5 for calling the DataFrameToParquet obj's underlying member method code with example usage: obj.index() and returns: self