System.Collections.Frozen.DefaultFrozenDictionary<TKey, TValue> sealed class DefaultFrozenDictionary<TKey, TValue> : KeysAndValuesFrozenDictionary<TKey, TValue>, IDictionary<TKey, TValue>, ICollection<KeyValuePair<TKey, TValue>>, IEnumerable<KeyValuePair<TKey, TValue>>, IEnumerable Documentation Code