How to make a function called 1 time in angular like regular JS?

Question

Angular

when I call this function, it always adds one and gets a growing number, although it was called only once.

count(){
    return this.idLocalFiles++;
  }

I want to call it and have it count once and add one each time it is called.

{{count()}} // 0
{{count()}} // 1
{{count()}} // 2
{{count()}} // 3