Scale this point by factor as if it were a vector.
Important Note: This function accepts a num as its argument only so
that you can scale Point<double> objects by an int factor. Because the
star operator always returns the same type of Point that originally called
it, passing in a double factor on a Point<int> causes a
runtime error in checked mode.
Source
Point<T> operator *(num factor) {
return new Point<T>(x * factor, y * factor);
}