code: def build_server_model():
      input1 = Input(shape=(1))
      input2 = Input(shape=(1))
      x = tf.stack([input1, input2])
      x = tf.reduce_sum(
          x, 0
      )  # above two act as interactive layer, CAddTable
      outputs = tf.sigmoid(x)
      return Model(
          inputs=[input1, input2],
          outputs=outputs,
          name="vfl_server_model",
      )
  
file_path: BigDL/python/ppml/example/tensorflow_nn_lr/tensorflow_nn_lr_1.py
imports: import logging
  from typing import List
  import numpy
  import pandas
  import click
  import tensorflow
  from tensorflow import Tensor
  from tensorflow.keras.layers import Dense
  from tensorflow.keras import Model, Input
  from bigdl.ppml.fl.estimator import Estimator
  from bigdl.ppml.fl.nn.fl_context import init_fl_context
  from bigdl.ppml.fl.psi.psi_client import PSI
label_desc: Use image node_id 2 for calling a global function with example usage: build_server_model() and returns: Model