def find_page_of_state_m(self, state_m):
        """Return the identifier and page of a given state model

        :param state_m: The state model to be searched
        :return: page containing the state and the state_identifier
        """
        for state_identifier, page_info in list(self.tabs.items()):
            if page_info['state_m'] is state_m:
                return page_info['page'], state_identifier
        return None, None