code: def test_serialize(Estimator, serialize_test, hyperparameters):
      serialize_test(Estimator, hyperparameters)
  
imports: import pytest
  from gluonts.mx.model.canonical._estimator import CanonicalRNNEstimator, MLPForecasterEstimator
label_desc: Use image node_id 4 for calling a global function with example usage: test_serialize(Estimator, serialize_test, hyperparameters) without return types