How to create Angular 2+ toggle for multiple buttons?

Hello I need to create toggle buttons, but when I click first button active class works for both element.

HTML

 <button [class.active]="k" (click)="toggle()">1</button>
 <button [class.active]="k" (click)="toggle()">2</button>

TS

k: boolean = false;
toggle(): void {
   this.k = !this.k;
}

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Source Url How to create Angular 2+ toggle for multiple buttons?