code: def plot_boundaries(self, **kwargs):
          
          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()
docs: Plots boundaries of a mesh