code: def cross_section_mesh(mesh, plane, dist_tol=1e-8):
      
      # Set of all triangles
      T = set(range(len(mesh.tris)))
      # List of all cross-section polylines
      P = []
  
      while len(T) > 0:
          tid = T.pop()
  
          intersections = compute_triangle_plane_intersections(
                  mesh, tid, plane, dist_tol)
  
          if len(intersections) == 2:
              for intersection in intersections:
                  p, T = _walk_polyline(tid, intersection, T, mesh, plane,
                                        dist_tol)
                  if len(p) > 1:
                      P.append(np.array(p))
      return P
docs: Args:
          mesh: A geom.TriangleMesh instance
          plane: The cut plane : geom.Plane instance
          dist_tol: If two points are closer than dist_tol, they are considered
                    the same