static TreeView<GazelleTree> gazelle_treeView(final GazelleTree t) {
  ret t == null ? null : new TreeView<GazelleTree> {
    GazelleTree node() { ret t; }
    L<TreeView<GazelleTree>> children() { ret map gazelle_treeView(t.children); }
    TreeView<GazelleTree> parent() { ret gazelle_treeView(t.parent); }
  };
}

static TreeView<GazelleTree> gazelle_treeView(final L<GazelleTree> l) {
  ret new TreeView<GazelleTree> {
    GazelleTree node() { null; }
    L<TreeView<GazelleTree>> children() { ret map gazelle_treeView(l); }
    TreeView<GazelleTree> parent() { null; }
  };
}