@Override
        public @Nullable Object execute(Iterator<?> iterator) {
          iterator.remove();
          return null;
        }
      };

  private static final IteratorOperation NEXT_METHOD =
      new IteratorOperation() {
        @Override
        public @Nullable Object execute(Iterator<?> iterator) {
          return iterator.next();
        }
      };

        ListIterator<T> iterator = listIterator();
        while (iterator.previousIndex() < index && iterator.hasNext()) {
            iterator.next();
        }
        return iterator;
    }

    @Override
    public void add(int index, T element) {
        modCount++;
        ListIterator<T> iterator = iteratorAt(index - 1);
        if (iterator.nextIndex() == index) {

	return MapSet[T]{
		m: m,
	}
}

func (s MapSet[T]) Add(t T) {
	s.m.Put(t, struct{}{})
}

func (s MapSet[T]) Len() int {
	return s.m.Len()
}

func (s MapSet[T]) Iterate(cb func(T) bool) {
	s.m.Iterate(func(p a.Pair[T, struct{}]) bool {
		return cb(p.L)
	})
}

func main() {
	x := FromMap[int](a.NewHashMap[int, struct{}](1))
	Copy[int](x)

    assertFalse(getMap().entrySet().iterator().hasNext());
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION, SUPPORTS_REMOVE})
  @CollectionSize.Require(SEVERAL)
  public void testClearConcurrentWithEntrySetIteration() {
    try {
      Iterator<Entry<K, V>> iterator = getMap().entrySet().iterator();
      getMap().clear();
      iterator.next();
      fail("Expected ConcurrentModificationException");

    try {
      iterator.next();
      fail();
    } catch (NoSuchElementException expected) {
    }
    try {
      iterable.iterator();
      fail();
    } catch (IllegalStateException expected) {
    }
  }

  public void testOf_one() {
    Iterable<String> iterable = MinimalIterable.of("a");
    Iterator<String> iterator = iterable.iterator();
    assertTrue(iterator.hasNext());

   * endpoints of a directed edge).
   */
  public abstract boolean isOrdered();

  /** Iterates in the order {@link #nodeU()}, {@link #nodeV()}. */
  @Override
  public final UnmodifiableIterator<N> iterator() {
    return Iterators.forArray(nodeU, nodeV);
  }

  /**
   * Two ordered {@link EndpointPair}s are equal if their {@link #source()} and {@link #target()}

import java.util.Collections;
import java.util.Iterator;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A utility for testing an Iterator implementation by comparing its behavior to that of a "known
 * good" reference implementation. In order to accomplish this, it's important to test a great
 * variety of sequences of the {@link Iterator#next}, {@link Iterator#hasNext} and {@link

 public:
  typedef ParamIterator<T> iterator;

  explicit ParamGenerator(ParamGeneratorInterface<T>* impl) : impl_(impl) {}
  ParamGenerator(const ParamGenerator& other) : impl_(other.impl_) {}

  ParamGenerator& operator=(const ParamGenerator& other) {
    impl_ = other.impl_;
    return *this;
  }

  iterator begin() const { return iterator(impl_->Begin()); }
  iterator end() const { return iterator(impl_->End()); }

import java.util.Collections;
import java.util.Iterator;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A utility for testing an Iterator implementation by comparing its behavior to that of a "known
 * good" reference implementation. In order to accomplish this, it's important to test a great
 * variety of sequences of the {@link Iterator#next}, {@link Iterator#hasNext} and {@link

      @Override
      protected Iterator<E> newTargetIterator() {
        resetCollection();
        return collection.iterator();
      }

      @Override
      protected void verify(List<E> elements) {
        expectContents(elements);
      }
    }.test();
  }

  public void testIteratorNoSuchElementException() {
    Iterator<E> iterator = collection.iterator();
    while (iterator.hasNext()) {