'Check if there is no occurence of this group of partner in the selected model
:param aggr_ids : stringified list of partner ids separated with a comma (sql array_agg)
:param models : dict mapping a model name with its foreign key with res_partner table'

@api.model
def _partner_use_in(self, aggr_ids, models):

    return any((self.env[model].search_count([(field, 'in', aggr_ids)]) for (model, field) in models.iteritems()))
