How to use the vcsi.vcsi.Config.metadata_font function in vcsi

def compose_contact_sheet(
        media_info,
        frames,
        args):
    """Creates a video contact sheet with the media information in a header
    and the selected frames arranged on a mxn grid with optional timestamps
    """
    desired_size = grid_desired_size(
        args.grid,
        media_info,
        width=args.vcs_width,
        horizontal_margin=args.grid_horizontal_spacing)
    width = args.grid.x * (desired_size[0] + args.grid_horizontal_spacing) - args.grid_horizontal_spacing
    height = args.grid.y * (desired_size[1] + args.grid_vertical_spacing) - args.grid_vertical_spacing

    header_font = load_font(args, args.metadata_font, args.metadata_font_size, Config.metadata_font)
    timestamp_font = load_font(args, args.timestamp_font, args.timestamp_font_size, Config.timestamp_font)

    header_lines = prepare_metadata_text_lines(
        media_info,
        header_font,
        args.metadata_horizontal_margin,
        width,
        template_path=args.metadata_template_path)

    line_spacing_coefficient = 1.2
    header_line_height = int(args.metadata_font_size * line_spacing_coefficient)
    header_height = 2 * args.metadata_margin + len(header_lines) * header_line_height

    if args.metadata_position == "hidden":
        header_height = 0

parser.add_argument(
        "-t", "--show-timestamp",
        action="store_true",
        help="display timestamp for each frame",
        dest="show_timestamp")
    parser.add_argument(
        "--metadata-font-size",
        help="size of the font used for metadata",
        dest="metadata_font_size",
        type=int,
        default=Config.metadata_font_size)
    parser.add_argument(
        "--metadata-font",
        help="TTF font used for metadata",
        dest="metadata_font",
        default=Config.metadata_font)
    parser.add_argument(
        "--timestamp-font-size",
        help="size of the font used for timestamps",
        dest="timestamp_font_size",
        type=int,
        default=Config.timestamp_font_size)
    parser.add_argument(
        "--timestamp-font",
        help="TTF font used for timestamps",
        dest="timestamp_font",
        default=Config.timestamp_font)
    parser.add_argument(
        "--metadata-position",
        help="Position of the metadata header. Must be one of ['top', 'bottom', 'hidden']",
        dest="metadata_position",
        type=metadata_position_type,