public static Option <TripleMap1 <TPrimaryKey, TSecondary, TTertiary, TValue> > Contingent(IEnumerable <Tuple <TPrimaryKey, TSecondary, TTertiary, TValue> > entries) =>
Map1.Contingent(entries.Select(x => Tuple.Create(x.Item1, Tuple.Create(x.Item2, x.Item3, x.Item4)))).Select(
p =>
new TripleMap1 <TPrimaryKey, TSecondary, TTertiary, TValue>(
p,
Map1.Insist(p.GetKeyValuePairs().Select(x => Tuple.Create(x.Item2.Item1, x.Item1))),
Map1.Insist(p.GetKeyValuePairs().Select(x => Tuple.Create(x.Item2.Item2, x.Item1)))));
public static TwinMap1 <TPrimaryKey, TSecondary, TValue> Build(Array1 <Tuple <TPrimaryKey, TSecondary, TValue> > entries) =>
Map1.Build(entries.Select(x => Tuple.Create(x.Item1, Tuple.Create(x.Item2, x.Item3)))).Let(
p =>
new TwinMap1 <TPrimaryKey, TSecondary, TValue>(
p,
Map1.Insist(p.GetKeyValuePairs().Select(x => Tuple.Create(x.Item2.Item1, x.Item1)))));