Update all the artists in the histogram. Subclassable to
        allow updating of further artists.

def _update_artists(self, key, hist, edges, hvals, widths, lims, ranges):
        """
        Update all the artists in the histogram. Subclassable to
        allow updating of further artists.
        """
        plot_vals = zip(self.handles['artist'], edges, hvals, widths)
        for bar, edge, height, width in plot_vals:
            if self.invert_axes:
                bar.set_y(edge)
                bar.set_width(height)
                bar.set_height(width)
            else:
                bar.set_x(edge)
                bar.set_height(height)
                bar.set_width(width)