checkNotNull(iterable);
    Iterators.checkNonnegative(position);
    if (iterable instanceof List) {
      List<? extends T> list = Lists.cast(iterable);
      return (position < list.size()) ? list.get(position) : defaultValue;
    } else {
      Iterator<? extends T> iterator = iterable.iterator();
      Iterators.advance(iterator, position);
      return Iterators.getNext(iterator, defaultValue);
    }
  }

     */
    public MultiIterator(final Iterator<E>... iterators) {
        assertArgumentNotNull("iterators", iterators);
        this.iterators = iterators;
    }

    @Override
    public boolean hasNext() {
        for (; index < iterators.length; ++index) {
            if (iterators[index].hasNext()) {
                return true;
            }
        }
        return false;
    }

### Iterators

The new [iter] package provides the basic definitions for working with
user-defined iterators.

The [slices] package adds several functions that work with iterators:
- [All](/pkg/slices#All) returns an iterator over slice indexes and values.
- [Values](/pkg/slices#Values) returns an iterator over slice elements.
- [Backward](/pkg/slices#Backward) returns an iterator that loops over
  a slice backward.

    checkNotNull(iterable);
    Iterators.checkNonnegative(position);
    if (iterable instanceof List) {
      List<? extends T> list = Lists.cast(iterable);
      return (position < list.size()) ? list.get(position) : defaultValue;
    } else {
      Iterator<? extends T> iterator = iterable.iterator();
      Iterators.advance(iterator, position);
      return Iterators.getNext(iterator, defaultValue);
    }
  }

            @Override
            @Nonnull
            public Iterator<File> iterator() {
                return new SingleDepthFileIterator(baseDir, filter);
            }
        };
    }

    private class SingleDepthFileIterator extends AbstractIterator<File> {

        private final Deque<Iterator<File>> stack = new ArrayDeque<Iterator<File>>();
        private final int targetSize;

  protected boolean standardRemove(@CheckForNull Object object) {
    Iterator<E> iterator = iterator();
    while (iterator.hasNext()) {
      if (Objects.equal(iterator.next(), object)) {
        iterator.remove();
        return true;
      }
    }
    return false;
  }

  /**
   * A sensible definition of {@link #removeAll} in terms of {@link #iterator}, using the iterator's

  protected boolean standardRemove(@CheckForNull Object object) {
    Iterator<E> iterator = iterator();
    while (iterator.hasNext()) {
      if (Objects.equal(iterator.next(), object)) {
        iterator.remove();
        return true;
      }
    }
    return false;
  }

  /**
   * A sensible definition of {@link #removeAll} in terms of {@link #iterator}, using the iterator's

        this.second = second;
    }

    @Override
    public boolean isEmpty() {
        return false;
    }

    @Override
    public Iterator<PluginRequestInternal> iterator() {
        return Iterators.concat(first.iterator(), second.iterator());
    }

    }

    @Override
    public Iterator<IncludeDirectives> iterator() {
        collectAll();

        Iterator<IncludeDirectives> initialDirectives = Iterators.singletonIterator(includeDirectives);
        if (visible == null || visible.isEmpty()) {
            return initialDirectives;
        }
        return Iterators.concat(initialDirectives, visible.values().iterator());
    }

  return %arg0 : tensor<!tf_type.variant>
}

// CHECK-LABEL: iterators
func.func private @iterators(%arg0 : tensor<!tf_type.variant>) {
  %0 = "tf.Iterator"() {container = "", output_shapes = [#tf_type.shape<200x28x28x1>, #tf_type.shape<200x10>], output_types = [f32, f32], shared_name = "_iterator1"} : () -> tensor<!tf_type.resource>