/guava/guava/src/com/google/common/collect/Sets.java
for ( E e : set1) { int size = 0;
int size = 0; for ( E e : set1 ) {
@Override public Stream<E> parallelStream() { return set1.parallelStream().filter(e -> !set2.contains(e)); } @Override public int size() { <extra_id_0> if (!set2.contains(e)) { size++; } } return size; }