message: Don't return 'const int', that's equivalent to int and causes a warning.
diff: @@ -175,7 +175,7 @@ class Alpha_complex {
  *
  * @return The number of vertices.
  */
  - const std::size_t number_of_vertices() const {
  + std::size_t number_of_vertices() const {
  return vertex_handle_to_iterator_.size();
  }
  