private static IEnumerable <Token> PartitionSequences(
IEnumerable <Token> tokens,
Func <string, Maybe <Tuple <DescriptorType, Maybe <int> > > > typeLookup)
{
return(from tseq in tokens.Pairwise(
(f, s) =>
f.IsName() && s.IsValue()
? typeLookup(f.Text).Return(info =>
info.Item1 == DescriptorType.Sequence
? new[] { f }.Concat(tokens.SkipWhile(t => t.Equals(f)).TakeWhile(v => v.IsValue()).Take(MaybeExtensions.Return(info.Item2, items => items, 0)))
: new Token[] { }, new Token[] { })
: new Token[] {})
from t in tseq
select t);
}