def mesh(isa, with_axis=False, ax=0):
    """plot mesh of I7/ISA7 model
    Args:
      isa: Isa7 object
    """
    from matplotlib.lines import Line2D
    if ax == 0:
        ax = plt.gca()
    ax.set_aspect('equal')
    for el in isa.elements:
        pts = [list(i) for i in zip(*[v.xy for v in el.vertices])]
        ax.add_line(Line2D(pts[0], pts[1], color='b', ls='-', lw=0.25))

    # for nc in isa.nodechains:
    #    pts = [list(i) for i in zip(*[(n.x, n.y) for n in nc.nodes])]
    #    ax.add_line(Line2D(pts[0], pts[1], color="b", ls="-", lw=0.25,
    #                       marker=".", ms="2", mec="None"))

    # for nc in isa.nodechains:
    #    if nc.nodemid is not None:
    #        plt.plot(*nc.nodemid.xy, "rx")

    ax.autoscale(enable=True)
    if not with_axis:
        ax.axis('off')