code: def testProvideClass_Singleton(self):
      class Foo:
          pass
  
      mod = module.DependencyModule()
      mod.provide_class(Foo, singleton=True)
      self.assertIs(
          mod.get(ANY_NAME, Foo),
          mod.get(ANY_NAME, Foo),
      )
  
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 14 for calling the ModuleTest obj's underlying member method code with example usage: obj.testProvideClass_Singleton() without return types