def _last_index(self, s):
        self.set_index(max(0, self._find_one_after_last_labeled_index() - 1))
def i1beta_up(i1, beta, up, ax=0):
    """creates a surface plot of up vs i1, beta"""
    if ax == 0:
        _create_3d_axis()
        ax = plt.gca()
    _plot_surface(ax, i1, beta, up,
                  (u'I1/A', u'Beta/°', u'Up/V'),
                  azim=60)