code: def testGet_MissingDependency_OptionalIsNone(self):
      mod = module.DependencyModule()
      self.assertIsNone(mod.get("x", Optional[int]))
  
imports: import dataclasses
  from typing import Optional, Union
  import tensorflow
  from tfx.utils.di import errors
  from tfx.utils.di import module
label_desc: Use image node_id 3 for calling the ModuleTest obj's underlying member method code with example usage: obj.testGet_MissingDependency_OptionalIsNone() without return types