code: def get_extensions(cls):
          
          assemblies = []
          for waldur_extension in pkg_resources.iter_entry_points('waldur_extensions'):
              extension_module = waldur_extension.load()
              if inspect.isclass(extension_module) and issubclass(extension_module, cls):
                  if not extension_module.is_assembly():
                      yield extension_module
                  else:
                      assemblies.append(extension_module)
          for assembly in assemblies:
              yield assembly
docs: Get a list of available extensions