code: def shift_and_pad(tensor, shift, axis=0):
      """Shifts and pads with zero along an axis.
  
      Example:
        shift_and_pad([1, 2, 3, 4], 2)  --> [0, 0, 1, 2]
        shift_and_pad([1, 2, 3, 4], -2) --> [3, 4, 0, 0]
  
      Args:
        tensor: Tensor; to be shifted and padded.
        shift: int; number of positions to shift by.
        axis: int; along which axis to shift and pad.
  
      Returns:
        A Tensor with the same shape as the input tensor.
      """
      shape = tensor.shape
      rank = len(shape)
      assert 0 <= abs(axis) < rank
  
      length = int(shape[axis])
      assert 0 <= abs(shift) < length
  
      paddings = [(0, 0)] * rank
      begin = [0] * rank
      size = [-1] * rank
  
      if shift > 0:
          paddings[axis] = (shift, 0)
          size[axis] = length - shift
      elif shift < 0:
          paddings[axis] = (0, -shift)
          begin[axis] = -shift
  
      ret = tf.pad(tf.slice(tensor, begin, size), paddings)
  
      return ret
  
file_path: tensor2tensor/tensor2tensor/models/research/transformer_aux.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from tensor2tensor.layers import common_layers
  from tensor2tensor.models import transformer
  from tensor2tensor.utils import registry
  import tensorflow.compat.v1
label_desc: Use image node_id 1 for calling a global function with example usage: shift_and_pad(tensor, shift, axis) and returns: ret