public IEnumerable <T> GetItems(byte[] lower, byte[] upper)
{
foreach (var pair in m_index.GetRange(lower, upper))
{
var items = pair.Value as HashSet <T>;
if (items != null)
{
foreach (T item in items)
{
yield return(item);
}
}
else
{
yield return((T)pair.Value);
}
}
}