docs: def get_domain(self):
          """
          :returns: opposite vertices of the bounding prism for this 
              object.
          :rtype: ndarray([min], [max])
          """
          if self.polyhedra != []:
              polyhedras_domain = np.vstack([poly.get_domain() 
                                            for poly in self.polyhedra])
          else:
              polyhedras_domain = np.ones((0, 3))
          points = np.vstack((self.surface.get_domain(), 
                              polyhedras_domain, 
                              self.set_of_points))
          return np.array([points.min(axis=0), points.max(axis=0)])