tiple values from the metric.

        Args:
            val: Either a single result from calling `metric.forward` or `metric.compute` or a list of these results.
                If no value is provided, will automatically call `metric.compute` and plot that result.
            ax: An matplotlib axis object. If provided will add plot to that axis

        Returns:
            Figure and Axes object

        Raises:
            ModuleNotFoundError:
                If `matplotlib` is not installed

        .. plot::
            :scale: 75

            >>> # Example plotting single value
            >>> import torch
            >>> from torchmetrics.image import SpectralAngleMapper
            >>> gen = torch.manual_seed(42)
            >>> preds = torch.rand([16, 3, 16, 16], generator=gen)
            >>> target = torch.rand([16, 3, 16, 16], generator=gen)
            >>> metric = SpectralAngleMapper()
            >>> metric.update(preds, target)
            >>> fig_, ax_ = metric.plot()

        .. plot::
            :scale: 75

            >>> # Example plotting multiple values
            >>> import torch
            >>> from torchmetrics.image import SpectralAngleMapper
            >>> gen = torch.manual_seed(42)
            >>> preds = torch.rand([16, 3, 16, 16], generator=gen)
            >>> target = torch.rand([16, 3, 16, 16], generator=gen)
            >>> metric = SpectralAngleMapper()
            >>> values = [ ]
            >>> for _ in range(10):
            ...     values.append(metric(preds, target))
            >>> fig_, ax_ = metric.plot(values)

        )