how to Change the shape of body dynamically

    const gravity = new b2Vec2(0, 10);
    
    world = new b2World(gravity);

    const bd_ground = new b2BodyDef();
    
    const ground = world.CreateBody(bd_ground);
    const shape = new b2EdgeShape();
    var xx=new b2Vec2(3, 4)
    shape.SetTwoSided(xx, new b2Vec2(6, 7));
    ground.CreateFixture(shape, 0);