public bool MoveNext()
{
bool moveNext = _source.MoveNext();
if (moveNext)
{
if (current.Index == -1)
{
current = new ItemIndexPair <T>(0, _source.Current);
}
else
{
current = current.Next(_source.Current);
}
}
return(moveNext);
}
public Enumerator(IEnumerator <T> source)
{
_source = source;
current = new ItemIndexPair <T>(-1, default(T));
}