Dart operator overloading complex types

complex.dart

class Complex {
  Complex(this.re, this.im);
  double re, im;
  operator +(Complex other) {
    return new Complex(re + other.re, im + other.im);
  }
  void Display( ) {
    print('$re,$im');
  }
}

main() {
   Complex a = new Complex( 1.2, 3.4 );
   Complex b = new Complex( 5.6, 7.8 );
   Complex c = new Complex( 0.0, 0.0 );
   c = a + b;
   c.Display();
}