Use quiver directly, and update README.google. This is so that we don't have to fork quiver_hashcode as well. BUG= R=whesse@google.com Review-Url: https://codereview.chromium.org/2944463002 .
const t = const Tuple2<String, int>('a', 10); print(t.item1); // prints 'a' print(t.item2); // prints '10'
final t1 = const Tuple2<String, int>('a', 10); final t2 = t1.withItem1('c'); // t2 is a new [Tuple2] object with item1 is 'c' and item2 is 10.