static Pair<Exp, Matching> nlLogic_iterate_x(NLLogicChecker_v2 c, Exp e, final Matching m, final Runnable onMatch) {
  if (e cast And) {
    c.iterate_single(e.a, m, r {
      Logic_iterate_x(e.b, m, onMatch)
    });
    ret;
  }
    
  c.iterate_single(e, m, onMatch);
}