def _to_dict(self):
        """Return a json dictionary representing this model."""
        _dict = {}
        if hasattr(self, 'refresh_cursor') and self.refresh_cursor is not None:
            _dict['refresh_cursor'] = self.refresh_cursor
        if hasattr(self, 'next_cursor') and self.next_cursor is not None:
            _dict['next_cursor'] = self.next_cursor
        if hasattr(self, 'refresh_url') and self.refresh_url is not None:
            _dict['refresh_url'] = self.refresh_url
        if hasattr(self, 'next_url') and self.next_url is not None:
            _dict['next_url'] = self.next_url
        if hasattr(self, 'total') and self.total is not None:
            _dict['total'] = self.total
        return _dict