code: def add_placeholder(self, var_name):
      var_val = getattr(self, var_name)
      setattr(
          self,
          var_name + "_placeholder",
          tf.placeholder(var_val.dtype, shape=var_val.get_shape()),
      )
      setattr(
          self,
          var_name + "_op",
          var_val.assign(getattr(self, var_name + "_placeholder")),
      )
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import tensorflow
  import bz2
  import PIL.Image
  from PIL import ImageFilter
  import numpy
  from keras.models import Model
  from keras.applications.vgg16 import VGG16, preprocess_input
  import keras.backend
  import traceback
  import external.stylegan2.dnnlib.tflib
  from core.landmark_handler import Landmark_Handler
  from core import arcface_handler
label_desc: Use image node_id 2 for calling the PerceptualModel obj's underlying member method code with example usage: obj.add_placeholder(var_name) without return types