loadUnits(index: number): Promise<number> {

        if (this.products[index].unitsLoaded) {
            //return Promise.resolve(index);
        }

        return this.requestUnits(this.products[index].id).then((res: b2b.UnitResponse[]) => {

            if (!this.products[index].units) {
               this.products[index].units = new Map<number, b2b.UnitMapElement>();
            }

            res.forEach(item => {

                if (!this.products[index].units.has(item.no)) {

                    this.products[index].units.set(item.no, {
                       auxiliaryUnit: item.unit
                    });
                }
            });

            this.products[index].unitsLoaded = true;

            return index;

        });

    }