class_docstr: A unittest class for testing Backdoor Poisoning attack.
code: def poison_func_3(self, x):
      return insert_image(
          x,
          backdoor_path=self.backdoor_path,
          size=(5, 5),
          random=False,
          x_shift=3,
          y_shift=3,
      )
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import os
  import logging
  import unittest
  import numpy
  from art.attacks.poisoning.backdoor_attack import PoisoningAttackBackdoor
  from art.attacks.poisoning.perturbations import add_pattern_bd, add_single_bd, insert_image
  from art.utils import to_categorical
  from tests.utils import TestBase, master_seed, get_image_classifier_kr
label_desc: Use image node_id 5 for calling the TestBackdoorAttack obj's underlying member method code with example usage: obj.poison_func_3(x) and returns: insert_image