def get_groups_count(self, field=None):
        '''
        Returns 'matches' from group response.

                If grouping on more than one field, provide the field argument to specify which count you are looking for.
        '''
        field = field if field else self._determine_group_field(field)
        if 'matches' in self.data['grouped'][field]:
            return self.data['grouped'][field]['matches']
        raise ValueError("group matches not found in response")
Returns 'matches' from group response.

                If grouping on more than one field, provide the field argument to specify which count you are looking for.