def _deprecateReactor(self, reactor):
        """
        Deprecate C{iterate}, C{crash} and C{stop} on C{reactor}. That is,
        each method is wrapped in a function that issues a deprecation
        warning, then calls the original.

        @param reactor: The Twisted reactor.
        """
        self._reactorMethods = {}
        for name in ['crash', 'iterate', 'stop']:
            self._reactorMethods[name] = getattr(reactor, name)
            setattr(reactor, name, self._makeReactorMethod(name))

        Deprecate C{iterate}, C{crash} and C{stop} on C{reactor}. That is,
        each method is wrapped in a function that issues a deprecation
        warning, then calls the original.

        @param reactor: The Twisted reactor.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/_asynctest.py