assertEquals(
        "next() should still return first element after peeking", "A", peekingIterator.next());

    assertEquals("Should be able to peek() at middle element", "B", peekingIterator.peek());
    assertEquals(
        "Should be able to peek() middle element multiple times", "B", peekingIterator.peek());
    assertEquals(
        "next() should still return middle element after peeking", "B", peekingIterator.next());

   *
   * @deprecated Prefer {@linkplain ExecutionError(Error)} a constructor that accepts a cause: Users
   *     of this class typically expect for instances to have a non-null cause. At the moment, you
   *     can <i>usually</i> still preserve behavior by passing an explicit {@code null} cause. Note,
   *     however, that passing an explicit {@code null} cause prevents anyone from calling {@link

    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked(1);
      cache.getUnchecked(2);

      Set<Object> keys = cache.asMap().keySet();
      // We don't know whether these are still in the cache, so we can't assert on the return
      // values of these removes, but the cache should be empty after the removes, regardless.
      keys.remove(1);
      keys.remove(2);
      assertFalse(keys.remove(null));

          .put("MD5", Hashing.md5())
          .put("SHA", Hashing.sha1()) // Not the official name, but still works
          .put("SHA1", Hashing.sha1()) // Not the official name, but still works
          .put("sHa-1", Hashing.sha1()) // Not the official name, but still works
          .put("SHA-1", Hashing.sha1())
          .put("SHA-256", Hashing.sha256())
          .put("SHA-384", Hashing.sha384())

 *       cancel} on the {@code Future}). So beware: <i>Even if you cancel every preceding {@code
 *       Future} returned by this class, the next task may still have to wait.</i>.
 *   <li>Once an {@code AsyncCallable} returns a {@code Future}, this class considers that task to
 *       be "done" as soon as <i>that</i> {@code Future} completes in any way. Notably, a {@code

 * rarely use it directly, in part because it does not provide direct access to the {@code Future}
 * result. (If you want such access, you may prefer {@link Futures#addCallback
 * Futures.addCallback}.) Still, direct {@code addListener} calls are occasionally useful:
 *
 * <pre>{@code
 * final String name = ...;
 * inFlight.add(name);
 * ListenableFuture<Result> future = service.query(name);

  @Override
  @J2ktIncompatible // serialization
  @GwtIncompatible // serialization
  Object writeReplace() {
    return super.writeReplace();
  }

  // No longer used for new writes, but kept so that old data can still be read.
  @GwtIncompatible // serialization
  @J2ktIncompatible
  @SuppressWarnings("unused")
  private static class KeySetSerializedForm<K> implements Serializable {
    final ImmutableMap<K, ?> map;

    assertEquals(
        "next() should still return first element after peeking", "A", peekingIterator.next());

    assertEquals("Should be able to peek() at middle element", "B", peekingIterator.peek());
    assertEquals(
        "Should be able to peek() middle element multiple times", "B", peekingIterator.peek());
    assertEquals(
        "next() should still return middle element after peeking", "B", peekingIterator.next());

 * of {@link java.util.Formatter} specifiers. However, note that if the number of arguments does not
 * match the number of occurrences of {@code "%s"} in the format string, {@code Verify} will still
 * behave as expected, and will still include all argument values in the error message; the message
 * will simply not be formatted exactly as intended.
 *
 * <h3>More information</h3>
 *

            return EndpointPair.unordered(requireNonNull(node), otherNode);
          }
        }
        // Add to visited set *after* processing neighbors so we still include self-loops.
        visitedNodes.add(node);
        if (!advance()) {
          visitedNodes = null;
          return endOfData();
        }
      }
    }
  }