s_t1 = np.append(x_t1, s_t[:, :, :, :3], axis=3) or s_t1 = np.append(s_t[:, :, :, :3], x_t1, axis=3)?

[Jinke He]

When stacking the last four frames into one array, why using s_t1 = np.append(x_t1, s_t[:, :, :, :3], axis=3) rather than s_t1 = np.append(s_t[:, :, :, :3], x_t1, axis=3)? Will it make a difference? Thank you.