sclass NumberPt is IDoublePt {
  Number x, y;
  
  *() {}
  *(Point p) { x = p.x; y = p.y; }
  *(Pt    p) { x = p.x; y = p.y; }
  *(double *x, double *y) {}
  
  [stdEq]
  
  toString {
    ret x + ", " + y;
  }
  
  double length() { ret sqrt(sqr(x_dbl())+sqr(y_dbl())); }
  
  public double x_double aka x_dbl() { ret x.doubleValue(); }
  public double y_double aka y_dbl() { ret y.doubleValue(); }
}