Determines whether or not there are more pages with results.

        Returns:
            bool: Whether the iterator has more pages.

def _has_next_page(self):
        """Determines whether or not there are more pages with results.

        Returns:
            bool: Whether the iterator has more pages.
        """
        if self.page_number == 0:
            return True

        if self.max_results is not None:
            if self.num_results >= self.max_results:
                return False

        # Note: intentionally a falsy check instead of a None check. The RPC
        # can return an empty string indicating no more pages.
        return True if self.next_page_token else False