def get_width(image):
    """get_width(image) -> integer width of the image (number of columns).

    Input image must be rectangular list of lists. The width is
    taken to be the length of the first row of pixels. If the image is
    empty, then the width is defined to be 0.
    """
    if len(image) == 0:
        return 0
    else:
        return len(image[0])