Perform pixel-shuffling on the input.

def hybrid_forward(self, F, x):
        """Perform pixel-shuffling on the input."""
        f = self._factor
                                             # (N, C*f, W)
        x = F.reshape(x, (0, -4, -1, f, 0))  # (N, C, f, W)
        x = F.transpose(x, (0, 1, 3, 2))     # (N, C, W, f)
        x = F.reshape(x, (0, 0, -3))         # (N, C, W*f)
        return x