/// <inheritdoc/> public IEnumerator <KeyValuePair <TKey, BigInteger> > GetEnumerator() => _underlying.Select(x => new KeyValuePair <TKey, BigInteger>(x.Key, x.Value.Value)).GetEnumerator();
public IEnumerator <KeyValuePair <TKey, IImmutableSet <TValue> > > GetEnumerator() => Underlying.Select(x => new KeyValuePair <TKey, IImmutableSet <TValue> >(x.Key, x.Value.Elements)).GetEnumerator();