code: def xor_block(block):
      g = lcg()
      randblock = (
          np.array([next(g) for _ in range(np.product(block.shape))])
          .astype(np.uint8)
          .reshape(block.shape)
      )
      return np.bitwise_xor(block.astype(np.uint8), randblock & 0x0F)
  
imports: import base64
  import json
  import warnings
  import numpy
  import zlib
  from PIL import Image, ImageDraw
  import torch
label_desc: Use image node_id 4 for calling a global function with example usage: xor_block(block) and returns: np