def test_update_xy(v: Vector, x: float, y: float): assert v.update(x=x, y=y) == (x, y)
def test_update_x(v: Vector, x: float): assert v.update(x=x) == (x, v.y)
def test_update_y(v: Vector, y: float): assert v.update(y=y) == (v.x, y)