protected override ImmSet <T> Difference(ImmSet <T> other) { return(Root.SymDifference(other.Root, Lineage.Mutable()).Wrap(EqualityComparer)); }
protected override ImmMap <TKey, TValue> Difference(ImmMap <TKey, TValue> other) { other.CheckNotNull("other"); return(_root.SymDifference(other._root, Lineage.Mutable()).WrapMap(_equality)); }