code: static Matcher removeTrueInSequence(Matcher matcher) {
      if (matcher instanceof SeqMatcher) {
        List<Matcher> matchers = matcher.<SeqMatcher>as().matchers();
        List<Matcher> ms = new ArrayList<>();
        for (Matcher m : matchers) {
          if (!(m instanceof TrueMatcher)) {
            ms.add(m);
          }
        }
        return SeqMatcher.create(ms);
      }
      return matcher;
    }
docs: The true matcher is sometimes used as a placeholder while parsing. For sequences it isn't
  needed and it is faster to leave them out.