Usage example const t = Tuple2<String, int>('a', 10); print(t.item1); // prints 'a' print(t.item2); // prints '10' const t1 = Tuple2<String, int>('a', 10); final t2 = t1.withItem1('c'); // t2 is a new [Tuple2] object with item1 is 'c' and item2 is 10.
