def draw_multi_line(cr, draw_stroke, lines):
    """
    Draw multiple lines.

    A line is tuple

    - width of a line
    - collection of points

    :param cr: Cairo context.
    :param draw_stroke: Drawing stroke function (i.e. line or filled area).
    :param lines: Collection of lines to draw.
    """
    for width, points in lines:
        cr.new_path()
        cr.set_line_width(width)
        for x, y in points:
            cr.line_to(x, y)
        draw_stroke()
