A Voronoi diagram is generated by a set of points. If the distance metric is changed from Euclidean distance $d_2 = \sqrt{(x_2-x_1)^2 + (y_2-y_1)^2}$ to Manhattan distance $d_1 = |x_2-x_1| + |y_2-y_1|$, what is the shape of the Voronoi edge between two points $(0,0)$ and $(2,0)$?