public static void Swap(this PeopleByAge p, nint i, nint j)
{
var tmp = p[i];
p[i] = p[j];
p[j] = tmp;
}
public static bool Less(this PeopleByAge p, nint i, nint j)
{
return(p[i].Age < p[j].Age);
}
public static nint Len(this PeopleByAge p)
{
return(len(p));
}
public static void Swap(this PeopleByAge p, nint i, nint j)
{
(p[i], p[j]) = (p[j], p[i]);
}