/// <summary>
/// Removes all <see cref="Versioned{T}"/> entries identified by given <paramref name="timestamps"/>
/// and returns an updated <see cref="ORSet{T}"/>.
/// </summary>
public ORSet <T> Remove(ImmutableHashSet <VectorTime> timestamps) =>
new ORSet <T>(Versioned.Where(x => !timestamps.Contains(x.VectorTimestamp)).ToImmutableHashSet());