static <A> WithTrail<A> firstTransformersResult_trailEnabled(L<IF1<A, WithTrail<A>>> transformers, A a) {
  fOr (IF1<A, WithTrail<A>> f : transformers)
    if (f != null) {
      WithTrail<A> b = f.get(a);
      if (b != null)
        ret b;
    }
  null;
}