public <R extends Set<T>> R unionInto(SetIterable<? extends T> set, R targetSet) {
return SetIterables.unionInto(this, set, targetSet);
}
public ImmutableSortedSet<T> union(SetIterable<? extends T> set) {
return SetIterables.unionInto(this, set, TreeSortedSet.<T>newSet(this.comparator()))
.toImmutable();
}