code: public static <T, ET extends T, A1> DecomposableMatchBuilder1<List<T>, A1> headTail(
        DecomposableMatchBuilder1<ET, A1> head, MatchesExact<List<T>> tail) {
      List<Matcher<Object>> matchers = Lists.of(ArgumentMatchers.any(), ArgumentMatchers.eq(tail.t));
      return new DecomposableMatchBuilder1<List<T>, ET>(
          matchers, 0, new ListConsHeadTailFieldExtractor<>()).decomposeFirst(head);
    }
docs: Matches a list with a head element and a tail of remaining elements.
  
  <p>If matched, the {@code head} value is decomposed to 1.