How to use the spectral.get_rgb function in spectral

def display_dataset(img, gt, bands, labels, palette, vis):
    """Display the specified dataset.

    Args:
        img: 3D hyperspectral image
        gt: 2D array labels
        bands: tuple of RGB bands to select
        labels: list of label class names
        palette: dict of colors
        display (optional): type of display, if any

    """
    print("Image has dimensions {}x{} and {} channels".format(*img.shape))
    rgb = spectral.get_rgb(img, bands)
    rgb /= np.max(rgb)
    rgb = np.asarray(255 * rgb, dtype='uint8')

    # Display the RGB composite image
    caption = "RGB (bands {}, {}, {})".format(*bands)
    # send to visdom server
    vis.images([np.transpose(rgb, (2, 0, 1))],
                opts={'caption': caption})

def display_dataset(img, gt, bands, labels, palette, vis):
    """Display the specified dataset.

    Args:
        img: 3D hyperspectral image
        gt: 2D array labels
        bands: tuple of RGB bands to select
        labels: list of label class names
        palette: dict of colors
        display (optional): type of display, if any

    """
    print("Image has dimensions {}x{} and {} channels".format(*img.shape))
    rgb = spectral.get_rgb(img, bands)
    rgb /= np.max(rgb)
    rgb = np.asarray(255 * rgb, dtype='uint8')

    # Display the RGB composite image
    caption = "RGB (bands {}, {}, {})".format(*bands)
    # send to visdom server
    vis.images([np.transpose(rgb, (2, 0, 1))],
                opts={'caption': caption})