static GazelleTree gazelle_searchTreeUpwards(F1<GazelleTree, Bool> pred, GazelleTree tree) {
  if (tree == null) null;
  L<GazelleTree> l = tree.parent.children;
  int i = indexOf(l, tree);
  while (--i >= 0)
    if (isTrue_callF(l.get(i)))
      ret l.get(i);
  null;
}