code: def input(self):
      return self._input
  
imports: import numpy
  import pandas
  from ...None import opcodes
  from ...core import OutputType
  from ...serialization.serializables import KeyField, AnyField, Int8Field, Int64Field
  from ...utils import has_unknown_shape, no_default, pd_release_version
  from ..operands import DataFrameOperand, DataFrameOperandMixin
  from ..utils import parse_index, build_df, build_series, validate_axis
label_desc: Use image node_id 2 for calling the DataFrameShift obj's underlying member method code with example usage: obj.input() and returns: self