nsor
        >>> target = tensor([0, 1, 2, 3])
        >>> preds = tensor([0, 2, 1, 3])
        >>> accuracy = Accuracy(task="multiclass", num_classes=4)
        >>> accuracy(preds, target)
        tensor(0.5000)

        >>> target = tensor([0, 1, 2])
        >>> preds = tensor([[0.1, 0.9, 0], [0.3, 0.1, 0.6], [0.2, 0.5, 0.3]])
        >>> accuracy = Accuracy(task="multiclass", num_classes=3, top_k=2)
        >>> accuracy(preds, target)
        tensor(0.6667)

    