@CheckForNull Object value;
      @CheckForNull ValueHolder next;
    }

    /**
     * Holder object for values that cannot be null or empty (will be printed unconditionally). This
     * helps to shortcut most calls to isEmpty(), which is important because the check for emptiness
     * is relatively expensive. Use a subtype so this also doesn't need any extra storage.
     */

    }

    @Override
    public String toString() {
      return "IsOdd";
    }
  }

  /**
   * Generates a new Predicate per call.
   *
   * <p>Creating a new Predicate each time helps catch cases where code is using {@code x == y}
   * instead of {@code x.equals(y)}.
   */
  private static IsOdd isOdd() {
    return new IsOdd();
  }

  /*
   * Tests for Predicates.alwaysTrue().
   */

   * future changes to it will alter the behavior of the predicate.
   *
   * <p>This method can technically accept any {@code Collection<?>}, but using a typed collection
   * helps prevent bugs. This approach doesn't block any potential users since it is always possible
   * to use {@code Predicates.<Object>in()}.
   *
   * @param target the collection that may contain the function input
   */

  /** Constructor for use by subclasses. */
  protected AbstractFuture() {}

  // Gets and Timed Gets
  //
  // * Be responsive to interruption
  // * Don't create Waiter nodes if you aren't going to park, this helps reduce contention on the
  //   waiters field.
  // * Future completion is defined by when #value becomes non-null/non SetFuture
  // * Future completion can be observed if the waiters field contains a TOMBSTONE

      @CheckForNull Object value;
      @CheckForNull ValueHolder next;
    }

    /**
     * Holder object for values that cannot be null or empty (will be printed unconditionally). This
     * helps to shortcut most calls to isEmpty(), which is important because the check for emptiness
     * is relatively expensive. Use a subtype so this also doesn't need any extra storage.
     */

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Static convenience methods that help a method or constructor check whether it was invoked
 * correctly (that is, whether its <i>preconditions</i> were met).
 *
 * <p>If the precondition is not met, the {@code Preconditions} method throws an unchecked exception
 * of a specified type, which helps the method in which the exception was thrown communicate that

    taskFuture.addListener(listener, directExecutor());

    return outputFuture;
  }

  enum RunningState {
    NOT_RUN,
    CANCELLED,
    STARTED,
  }

  /**
   * This class helps avoid a StackOverflowError when large numbers of tasks are submitted with
   * {@link MoreExecutors#directExecutor}. Normally, when the first future completes, all the other

 *
 * Note that each chaining method returns a new ordering instance which is backed by the previous
 * instance, but has the chance to act on values <i>before</i> handing off to that backing instance.
 * As a result, it usually helps to read chained ordering expressions <i>backwards</i>. For example,
 * when {@code compare} is called on the above ordering:
 *
 * <ol>

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Static convenience methods that help a method or constructor check whether it was invoked
 * correctly (that is, whether its <i>preconditions</i> were met).
 *
 * <p>If the precondition is not met, the {@code Preconditions} method throws an unchecked exception
 * of a specified type, which helps the method in which the exception was thrown communicate that

            if (value != null) {
              return Maps.immutableEntry(getKey(index), value);
            }
          }
          return endOfData();
        }
      };
    }

    // redeclare to help optimizers with b/310253115
    @SuppressWarnings("RedundantOverride")
    @J2ktIncompatible // serialization
    @Override
    @GwtIncompatible // serialization
    Object writeReplace() {