code: def triangle_intersects_plane(mesh, tid, plane):
      
      dists = [point_to_plane_dist(mesh.verts[vid], plane)
               for vid in mesh.tris[tid]]
      side = np.sign(dists)
      return not (side[0] == side[1] == side[2])
docs: Returns true if the given triangle is cut by the plane. This will return
      false if a single vertex of the triangle lies on the plane