public static IDictionary <T1, T2> SubDictionary <T1, T2>(this IDictionary <T1, T2> originalDictionary, T1 startKeyInclusive, T1 endKeyInclusive)
{
var head = originalDictionary.Head(startKeyInclusive, false);
var tail = originalDictionary.Tail(endKeyInclusive, false);
var tmp = originalDictionary.Clone();
tmp.Remove(head.Keys.ToArray <T1>());
tmp.Remove(tail.Keys.ToArray <T1>());
return(tmp);
}