docs: def fetch_points_of_sales(self, ticket=None):
          """
          Fetch all point of sales objects.
  
          Fetch all point of sales from the WS and store (or update) them
          locally.
  
          Returns a list of tuples with the format (pos, created,).
          """
          ticket = ticket or self.get_or_create_ticket('wsfe')
  
          client = clients.get_client('wsfe', self.is_sandboxed)
          response = client.service.FEParamGetPtosVenta(
              serializers.serialize_ticket(ticket),
          )
          check_response(response)
  
          results = []
          for pos_data in response.ResultGet.PtoVenta:
              results.append(PointOfSales.objects.update_or_create(
                  number=pos_data.Nro,
                  issuance_type=pos_data.EmisionTipo,
                  owner=self,
                  defaults={
                      'blocked': pos_data.Bloqueado == 'N',
                      'drop_date': parsers.parse_date(pos_data.FchBaja),
                  }
              ))
  
          return results