code: def get_estimator(workers_per_node=2, model_fn=model_creator):
      estimator = Estimator.from_keras(
          model_creator=model_fn,
          config={"lr": 1e-3},
          workers_per_node=workers_per_node,
          backend="ray",
      )
      return estimator
  
imports: import math
  import os
  import shutil
  import tempfile
  import pytest
  from unittest import TestCase
  import tensorflow
  import numpy
  from bigdl.orca.data.pandas import read_csv
  from bigdl.orca.data import SparkXShards, XShards
  from bigdl.orca.data.tf.data import Dataset
  from bigdl.orca.learn.tf2 import Estimator
  from bigdl.orca.ray import OrcaRayContext
  from bigdl.orca import OrcaContext
label_desc: Use image node_id 14 for calling a global function with example usage: get_estimator(workers_per_node, model_fn) and returns: estimator