code: def test_serial_prediction(self):
      graph = DotProductPredictionGraph()
      array_1 = np.array(
          [
              [1.0, 1.0],
              [10.0, 10.0],
              [-1.0, 1.0],
          ]
      )
      array_2 = np.array(
          [
              [1.0, 1.0],
              [-1.0, -1.0],
              [-1.0, 1.0],
          ]
      )
  
      x_user = np.array([0, 0, 0, 1, 1, 1, 2, 2, 2])
      x_item = np.array([0, 1, 2, 0, 1, 2, 0, 1, 2])
  
      result = graph.connect_serial_prediction_graph(
          tf_user_representation=array_1,
          tf_item_representation=array_2,
          tf_x_user=x_user,
          tf_x_item=x_item,
      ).eval(session=self.session)
  
      expected_result = np.array(
          [2.0, -2.0, 0.0, 20.0, -20.0, 0.0, 0.0, 0.0, 2.0]
      )
      self.assertTrue(np.allclose(result, expected_result))
  
imports: import math
  import numpy
  from unittest import TestCase
  from tensorrec import TensorRec
  from tensorrec.prediction_graphs import DotProductPredictionGraph, CosineSimilarityPredictionGraph, EuclideanSimilarityPredictionGraph
  from tensorrec.session_management import get_session
  from tensorrec.util import generate_dummy_data_with_indicator
label_desc: Use image node_id 3 for calling the DotProductTestCase obj's underlying member method code with example usage: obj.test_serial_prediction() without return types