def _draw_vert_line(xdata, params, hide=False):
    """Draw vertical line."""
    if not hide:
        params['ax_vertline'].set_xdata(xdata)
        params['ax_hscroll_vertline'].set_xdata(xdata)
        params['vertline_t'].set_text('%0.2f  ' % xdata)
    params['ax_vertline'].set_visible(not hide)
    params['ax_hscroll_vertline'].set_visible(not hide)
    params['vertline_t'].set_visible(not hide)
