assertThat(DoubleMath.mean(ImmutableList.of(11, -22, 44, -88).iterator()))
        .isWithin(1.0e-10)
        .of(-13.75);
    assertThat(DoubleMath.mean(ImmutableList.of(11).iterator())).isWithin(1.0e-10).of(11);
    assertThrows(
        IllegalArgumentException.class,
        () -> DoubleMath.mean(ImmutableList.<Integer>of().iterator()));
  }

  @GwtIncompatible // DoubleMath.mean

  private int position;

  /** Returns the element with the specified index. This method is called by {@link #next()}. */
  @ParametricNullness
  protected abstract E get(int index);

  /**
   * Constructs an iterator across a sequence of the given size whose initial position is 0. That
   * is, the first call to {@link #next()} will return the first element (or throw {@link
   * NoSuchElementException} if {@code size} is zero).
   *

          .put(CharSink.class, NullByteSink.INSTANCE.asCharSink(UTF_8))
          // All collections are immutable empty. So safe for any type parameter.
          .put(Iterator.class, ImmutableSet.of().iterator())
          .put(PeekingIterator.class, peekingIterator(ImmutableSet.of().iterator()))
          .put(ListIterator.class, ImmutableList.of().listIterator())
          .put(Iterable.class, ImmutableSet.of())

        } else if (targetLocations == null) {
            locations = sourceLocations;
        } else {
            locations = new java.util.LinkedHashMap<>();
            for (java.util.Iterator<Integer> it = indices.iterator(); it.hasNext(); ) {
                InputLocation location;
                Integer index = it.next();
                if (index.intValue() < 0) {

    List<Predicate<Object>> list = new ArrayList<>();
    Iterable<Predicate<Object>> iterable =
        new Iterable<Predicate<Object>>() {
          @Override
          public Iterator<Predicate<Object>> iterator() {
            return list.iterator();
          }
        };
    Predicate<Object> predicate = Predicates.and(iterable);
    assertTrue(predicate.apply(1));
    list.add(Predicates.alwaysFalse());

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.jspecify.annotations.Nullable;

/**
 * Note this class is a copy of {@link com.google.common.collect.AbstractIterator} (for dependency
 * reasons).
 */
@GwtCompatible
abstract class AbstractIterator<T extends @Nullable Object> implements Iterator<T> {
  private State state = State.NOT_READY;

  }

  @Override
  public @Nullable K lastKey() {
    return sortedDelegate.lastKey();
  }

  @Nullable K higher(K k) {
    Iterator<K> iterator = keySet().tailSet(k).iterator();
    while (iterator.hasNext()) {
      K tmp = iterator.next();
      if (comparator().compare(k, tmp) < 0) {
        return tmp;
      }
    }
    return null;
  }

  @Override

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Deque;
import java.util.Iterator;
import org.jspecify.annotations.Nullable;

/**
 * A deque which forwards all its method calls to another deque. Subclasses should override one or

    }
    return (node == header || !range.contains(node.getElement())) ? null : node;
  }

  @Override
  Iterator<E> elementIterator() {
    return Multisets.elementIterator(entryIterator());
  }

  @Override
  Iterator<Entry<E>> entryIterator() {
    return new Iterator<Entry<E>>() {
      @Nullable AvlNode<E> current = firstNode();
      @Nullable Entry<E> prevEntry;

      @Override

  }

  protected K getKeyForNullValue() {
    return getEntryNullReplaces().getKey();
  }

  private Entry<K, V> getEntryNullReplaces() {
    Iterator<Entry<K, V>> entries = getSampleElements().iterator();
    for (int i = 0; i < getNullLocation(); i++) {
      entries.next();
    }
    return entries.next();
  }

  /**