I have a question about my code:

I used ListView in my project, code like below:

```
<ListView class="list-group" [items]="countries" (itemTap)="onItemTap($event)"
    style="height:1250px">
    <ng-template let-country="item" let-i="index">
        <FlexboxLayout flexDirection="row" class="list-group-item">
            <Label [text]="country.name" class="list-group-item-heading"
                verticalAlignment="center" style="width: 60%"></Label>
            <Label [text]="country.price" class="list-group-item-heading"
                verticalAlignment="center" style="width: 60%"></Label>
            <Button (tap)="decrementQty($event)" text='-' style="width: 60%">
            </Button>
            <TextField row="1" col="1" class="textfield" [text]="qty"
                editable="false" style="width: 60%">
            </TextField>
            <Button (tap)="incrementQty($event)" text='+' style="width: 60%">
            </Button>
        </FlexboxLayout>
    </ng-template>
</ListView>

```

[Demo](https://play.nativescript.org/?template=play-ng&id=rVJyY4)

My question is: How to use index? So when I click button `(tap)="incrementQty($event)"` I want to increment Qty only in one row, not in all rows. For this I declare in ng-table index, but not function. Can you suggest me any solution please?