class_docstr: Pads a Numpy image to the given size
  Return a Numpy image / image pair
  Arguments
  ---------
  :param size: (tuple or list):
      size of crop
code: def __call__(self, x, y=None):
      shape_diffs = [
          int(np.ceil((i_s - d_s)))
          for d_s, i_s in zip(x.shape, self.size)
      ]
      shape_diffs = np.maximum(shape_diffs, 0)
      pad_sizes = [
          (int(np.ceil(s / 2.0)), int(np.floor(s / 2.0)))
          for s in shape_diffs
      ]
      x = np.pad(x, pad_sizes, mode="constant")
      if y is not None:
          y = np.pad(y, pad_sizes, mode="constant")
          return x, y
      return x
  
imports: import os
  import random
  import math
  import numpy
  import torch
label_desc: Use image node_id 2 for calling the PadNumpy obj's underlying member method code with example usage: obj.__call__(x, y) and returns: x, x,  y