code: def test_shift_by_zero(self, datetime_frame, frame_or_series):
      # shift by 0
      obj = tm.get_obj(datetime_frame, frame_or_series)
      unshifted = obj.shift(0)
      tm.assert_equal(unshifted, obj)
  
imports: import numpy
  import pytest
  import pandas
  from pandas import CategoricalIndex, DataFrame, Index, NaT, Series, date_range, offsets
  import pandas._testing
label_desc: Use image node_id 12 for calling the TestDataFrameShift obj's underlying member method code with example usage: obj.test_shift_by_zero(datetime_frame, frame_or_series) without return types