Get the event loop.

        This may be None or an instance of EventLoop.

def get_event_loop(self):
        """Get the event loop.

        This may be None or an instance of EventLoop.
        """
        if (self._event_loop is None and
            threading.current_thread().name == 'MainThread'):
            self._event_loop = self.new_event_loop()
        return self._event_loop