tuple library Null safety

Classes

Tuple1<T0>
Tuple2<T0, T1>
Tuple3<T0, T1, T2>
Tuple4<T0, T1, T2, T3>
Tuple5<T0, T1, T2, T3, T4>
Tuple6<T0, T1, T2, T3, T4, T5>
Tuple7<T0, T1, T2, T3, T4, T5, T6>