code: def test_parallel(self):
      self.assertIsInstance(
          self.exp.model_parts(type="difference", processes=2),
          dx.model_explanations.VariableImportance,
      )
      self.assertIsInstance(
          self.exp.model_parts(type="ratio", processes=2),
          dx.model_explanations.VariableImportance,
      )
      self.assertIsInstance(
          self.exp.model_parts(type="variable_importance", processes=2),
          dx.model_explanations.VariableImportance,
      )
  
imports: import unittest
  import numpy
  from plotly.graph_objs import Figure
  from sklearn.compose import ColumnTransformer
  from sklearn.impute import SimpleImputer
  from sklearn.neural_network import MLPClassifier
  from sklearn.pipeline import Pipeline
  from sklearn.preprocessing import StandardScaler, LabelEncoder, OneHotEncoder
  import dalex
  from dalex.model_explanations._model_performance.utils import *
  from dalex.model_explanations._variable_importance import utils
label_desc: Use image node_id 9 for calling the FeatureImportanceTestTitanic obj's underlying member method code with example usage: obj.test_parallel() without return types