Perform pixel-shuffling on the input.

def hybrid_forward(self, F, x):
        """Perform pixel-shuffling on the input."""
        # `transpose` doesn't support 8D, need other implementation
        f1, f2, f3 = self._factors
                                                              # (N, C*f1*f2*f3, D, H, W)
        x = F.reshape(x, (0, -4, -1, f1 * f2 * f3, 0, 0, 0))  # (N, C, f1*f2*f3, D, H, W)
        x = F.swapaxes(x, 2, 3)                               # (N, C, D, f1*f2*f3, H, W)
        x = F.reshape(x, (0, 0, 0, -4, f1, f2*f3, 0, 0))      # (N, C, D, f1, f2*f3, H, W)
        x = F.reshape(x, (0, 0, -3, 0, 0, 0))                 # (N, C, D*f1, f2*f3, H, W)
        x = F.swapaxes(x, 3, 4)                               # (N, C, D*f1, H, f2*f3, W)
        x = F.reshape(x, (0, 0, 0, 0, -4, f2, f3, 0))         # (N, C, D*f1, H, f2, f3, W)
        x = F.reshape(x, (0, 0, 0, -3, 0, 0))                 # (N, C, D*f1, H*f2, f3, W)
        x = F.swapaxes(x, 4, 5)                               # (N, C, D*f1, H*f2, W, f3)
        x = F.reshape(x, (0, 0, 0, 0, -3))                    # (N, C, D*f1, H*f2, W*f3)
        return x