internal Enumerator(FrameResponseHeaders collection) { _collection = collection; _bits = collection._bits; _state = 0; _current = default(KeyValuePair <string, StringValues>); _hasUnknown = collection.MaybeUnknown != null; _unknownEnumerator = _hasUnknown ? collection.MaybeUnknown.GetEnumerator() : default(Dictionary <string, StringValues> .Enumerator); }