message: Code review: remove reference and explicit type (instead of auto)
diff: @@ -1129,7 +1129,7 @@ class Simplex_tree {
  bool to_be_inserted = true;
  Filtration_value filt = simplex->second.filtration();
  // If all the boundaries are present, 'next' needs to be inserted
  - for (auto& border : boundary_simplex_range(simplex)) {
  + for (Simplex_handle border : boundary_simplex_range(simplex)) {
  Simplex_handle border_child = find_child(border, next->first);
  if (border_child == null_simplex()) {
  to_be_inserted=false;
  