code: def test_estimator_graph_checkpoint(self):
      import bigdl.orca.data.pandas
  
      tf.reset_default_graph()
  
      model = SimpleModel()
      file_path = os.path.join(resource_path, "orca/learn/ncf.csv")
      data_shard = bigdl.orca.data.pandas.read_csv(file_path)
  
      def transform(df):
          result = {
              "x": (df["user"].to_numpy(), df["item"].to_numpy()),
              "y": df["label"].to_numpy(),
          }
          return result
  
      data_shard = data_shard.transform_shard(transform)
  
      temp = tempfile.mkdtemp()
      model_dir = os.path.join(temp, "test_model")
  
      est = Estimator.from_graph(
          inputs=[model.user, model.item],
          labels=[model.label],
          loss=model.loss,
          optimizer=tf.train.AdamOptimizer(),
          metrics={"loss": model.loss},
          model_dir=model_dir,
      )
      est.fit(
          data=data_shard,
          batch_size=8,
          epochs=6,
          validation_data=data_shard,
          checkpoint_trigger=SeveralIteration(4),
      )
  
      est.sess.close()
  
      tf.reset_default_graph()
  
      model = SimpleModel()
  
      est = Estimator.from_graph(
          inputs=[model.user, model.item],
          labels=[model.label],
          loss=model.loss,
          optimizer=tf.train.AdamOptimizer(),
          metrics={"loss": model.loss},
          model_dir=model_dir,
      )
  
      est.load_orca_checkpoint(model_dir)
  
      est.fit(
          data=data_shard,
          batch_size=8,
          epochs=10,
          validation_data=data_shard,
      )
  
      result = est.evaluate(data_shard)
      assert "loss" in result
      print(result)
      shutil.rmtree(temp)
  
imports: import os
  import shutil
  import tempfile
  from unittest import TestCase
  import numpy
  import tensorflow
  from bigdl.orca.learn.trigger import SeveralIteration
  from pyspark.sql.context import SQLContext
  import bigdl.orca.data.pandas
  from bigdl.dllib.nncontext import init_nncontext
  from bigdl.orca import OrcaContext
  from bigdl.orca.data.tf.data import Dataset
  from bigdl.orca.learn.tf.estimator import Estimator
  from bigdl.dllib.utils.tf import save_tf_checkpoint, load_tf_checkpoint, get_checkpoint_state
label_desc: Use image node_id 8 for calling the TestEstimatorForGraph obj's underlying member method code with example usage: obj.test_estimator_graph_checkpoint() and returns: result