code: def ref_shift(x, shifts, border_mode):
      if shifts is None:
          shifts = (0,) * len(x.shape)
      return scipy_shift(x, shifts, mode=border_mode, order=1)
  
imports: import pytest
  import numpy
  from scipy.ndimage.interpolation import shift
  import nnabla.functions
  from nbla_test_utils import list_context
label_desc: Use image node_id 1 for calling a global function with example usage: ref_shift(x, shifts, border_mode) and returns: scipy_shift