def update_notes(self, **kwargs):
        """
        Updates the notes on the subscription without generating a change
        This endpoint also allows you to update custom fields:

            `
                sub.custom_fields[0].value = 'A new value'
                sub.update_notes()
            `
        """
        for key, val in iteritems(kwargs):
            setattr(self, key, val)
        url = urljoin(self._url, '/notes')
        self.put(url)