code: def test_firstresult_no_plugin(pm):
      """If no implementations/plugins have been registered for a firstresult
      hook the multi-call loop should return a None value.
      """
  
      class Api(object):
          @hookspec(firstresult=True)
          def hello(self, arg):
              "api hook 1"
  
      pm.add_hookspecs(Api)
      res = pm.hook.hello(arg=3)
      assert res is None
  
file_path: catboost/contrib/python/pluggy/py2/tests/test_invocations.py
imports: import pytest
  from pluggy import PluginValidationError, HookimplMarker, HookspecMarker
label_desc: Use image node_id 8 for calling a global function with example usage: test_firstresult_no_plugin(pm) without return types