So, in the Sequential model, what we see happen is as soon as one of these heme groups, for example, this one binds the oxygen, that heme group completely changes its shape, and that changes the shape of the entire polypeptide that contains the heme group. And that's why, when going from this structure to this structure, this entire square becomes a circle, because it changes its conformation. And not only that, but the nearby polypeptide chains will also change their confirmation slightly. And that tells us that their affinity for oxygen, which will also increase, which is what we see happening in nature. So if we add one more oxygen, this will basically change our shape. And this nearby structure will also change its polypeptide chain.