Point2D PointPlusVector(Point2D O, Vector2D v) { return PointXY(O.x + v.x, O.y + v.y); }
PointXY PointXY::operator+( const double& other ) const { return PointXY(x+other,y+other); }
PointXY PointXY::operator*( const double& other ) const { return PointXY(x*other,y*other); }
PointXY PointXY::operator+( const PointXY& other ) const { return PointXY(x+other.x,y+other.y); }