code: public static <A, B, EA extends A, A1> DecomposableMatchBuilder1<Tuple2<A, B>, A1> tuple2(
        DecomposableMatchBuilder1<EA, A1> a, MatchesExact<B> b) {
      List<Matcher<Object>> matchers = Lists.of(ArgumentMatchers.any(), ArgumentMatchers.eq(b.t));
      return new DecomposableMatchBuilder1<Tuple2<A, B>, EA>(
          matchers, 0, new Tuple2FieldExtractor<>()).decomposeFirst(a);
    }
docs: Matches a tuple of 2 elements.
  
  <p>If matched, the {@code a} value is decomposed to 1.