def _last_index(self, s):
        self.set_index(max(0, self._find_one_after_last_labeled_index() - 1))
def spel(isa, with_axis=False, ax=0):
    """plot super elements of I7/ISA7 model
    Args:
      isa: Isa7 object
    """
    from matplotlib.patches import Polygon
    if ax == 0:
        ax = plt.gca()
    ax.set_aspect('equal')
    for se in isa.superelements:
        ax.add_patch(Polygon([n.xy
                              for nc in se.nodechains
                              for n in nc.nodes],
                             color=isa.color[se.color], lw=0))

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