static L<PairS> gazelle_findEqualitiesInTree(final GazelleTree tree) {
  new L<PairS> out;
  for (GazelleTree t : treeView_allNodes(gazelle_treeView(tree)))
    if (t.rule() != null && contains(t.rule().comments, "equality"))
      out.add(pair(t.parent.line, t.line));
  ret out;
}