Plots boundaries of a mesh

def plot_boundaries(self, **kwargs):
        """ Plots boundaries of a mesh """
        edges = self.extract_edges()

        plotter = vtki.Plotter(off_screen=kwargs.pop('off_screen', False),
                               notebook=kwargs.pop('notebook', None))
        plotter.add_mesh(edges, 'r', style='wireframe', legend='Edges')
        plotter.add_mesh(self, legend='Mesh', **kwargs)
        return plotter.show()