# Codeblock 7b
    def reorder(self, x, scale=2):                      # ([1, 64, 26, 26])
        B, C, H, W = x.shape
        h, w = H // scale, W // scale

        x = x.reshape(B, C, h, scale, w, scale)         # ([1, 64, 13, 2, 13, 2])     
        x = x.transpose(3, 4)                           # ([1, 64, 13, 13, 2, 2])

        x = x.reshape(B, C, h * w, scale * scale)       # ([1, 64, 169, 4])
        x = x.transpose(2, 3)                           # ([1, 64, 4, 169])

        x = x.reshape(B, C, scale * scale, h, w)        # ([1, 64, 4, 13, 13])
        x = x.transpose(1, 2)                           # ([1, 4, 64, 13, 13])

        x = x.reshape(B, scale * scale * C, h, w)       # ([1, 256, 13, 13])

        return x