Convert duration to years?

[Nestor via Digitalmars-d-learn]

On Sunday, 15 January 2017 at 07:25:26 UTC, rikki cattermole 
wrote:
> So I had a go at this and found I struggled looking at "magic" 
> functions and methods.
> Turns out there is a much simpler answer.
>
> int getAge(int yyyy, int mm, int dd) {
>   import std.datetime;
>   auto t1 = cast(DateTime)SysTime(Date(yyyy, mm, dd));
>   auto t2 = cast(DateTime)Clock.currTime();
>
>   int numYears;
>   while(t2 > t1) {
>      t1.add!"years"(1);
>      numYears++;
>   }
>
>   return numYears;
> }


Well... correct me if I am wrong, but isn't t1.add!"years"(1) 
simply adding one year to t1?