code: def test_uninstantiated_registrable(self):
      experiment = {
          "my_registrable": {
              "_name": "ClassWithUnInstantiatedObject",
              "my_function": "$mock_function",
          }
      }
      e = ExperimentConfig(experiment)
      self.assertEqual(e["my_registrable"].my_function, mock_function)
      self.assertEqual(e["my_registrable"].my_function(), 5)
  
imports: import unittest
  from pathlib import Path
  from typing import Any, Dict, List
  from transfer_nlp.plugins.config import CallableInstantiationError, ExperimentConfig, LoopInConfigError, UnknownPluginException, UnknownReferenceError, register_plugin
label_desc: Use image node_id 4 for calling the RegistryTest obj's underlying member method code with example usage: obj.test_uninstantiated_registrable() without return types