code: def test_get_model_echo_model(self):
      registry = model_registry.ModelRegistry()
      model = registry.get_model(model_registry.ModelName.ECHO_MODEL)
      results = model.call_model(model_input="this_is_a_test")
      self.assertEqual("this_is_a_test", results.model_input)
  
      # Echo model returns the model_input as text results.
      self.assertEqual(["this_is_a_test"], results.text_results)
  
imports: from __future__ import annotations
  from absl.testing import absltest
  from google.generativeai.notebook import model_registry
label_desc: Use image node_id 1 for calling the ModelRegistryTest obj's underlying member method code with example usage: obj.test_get_model_echo_model() without return types