/** Runnable is not running and not queued for execution */
    IDLE,
    /** Runnable is not running, but is being queued for execution */
    QUEUING,
    /** runnable has been submitted but has not yet begun execution */
    QUEUED,
    RUNNING,
  }

  /** Underlying executor that all submitted Runnable objects are run on. */
  private final Executor executor;

  @GuardedBy("queue")

  /** Creates a new, empty {@link ExecutionList}. */
  public ExecutionList() {}

  /**
   * Adds the {@code Runnable} and accompanying {@code Executor} to the list of listeners to
   * execute. If execution has already begun, the listener is executed immediately.
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See

    }
  }

  /**
   * Removes a number of occurrences of the specified element from this multiset. If the multiset
   * contains fewer than this number of occurrences to begin with, all occurrences will be removed.
   *
   * @param element the element whose occurrences should be removed
   * @param occurrences the number of occurrences of the element to remove

  @GwtIncompatible(value = "java.util.regex.Pattern")
  public static Predicate<CharSequence> contains(Pattern pattern) {
    return new ContainsPatternPredicate(new JdkPattern(pattern));
  }

  // End public API, begin private implementation classes.

  // Package private for GWT serialization.
  enum ObjectPredicate implements Predicate<@Nullable Object> {
    /** @see Predicates#alwaysTrue() */
    ALWAYS_TRUE {
      @Override

    @CheckForNull Executor nextExecutor;
  }

  /**
   * Enqueues a task to run when the previous task (if any) completes.
   *
   * <p>Cancellation does not propagate from the output future to a callable that has begun to
   * execute, but if the output future is cancelled before {@link Callable#call()} is invoked,
   * {@link Callable#call()} will not be invoked.
   */
  public <T extends @Nullable Object> ListenableFuture<T> submit(

    }
  }

  /**
   * Removes a number of occurrences of the specified element from this multiset. If the multiset
   * contains fewer than this number of occurrences to begin with, all occurrences will be removed.
   *
   * @param element the element whose occurrences should be removed
   * @param occurrences the number of occurrences of the element to remove

      return false;
    }

    /*
     * Note that we allow (in contravention of a strict interpretation of the relevant RFCs) domain
     * parts other than the last may begin with a digit (for example, "3com.com"). It's important to
     * disallow an initial digit in the last part; it's the only thing that stops an IPv4 numeric
     * address like 127.0.0.1 from looking like a valid domain name.

 * <h4>Automatically closing</h4>
 *
 * You can extract a {@link Future} that represents the result of the last step in the pipeline by
 * calling {@link #finishToFuture()}. All objects the pipeline has captured for closing will begin
 * to be closed asynchronously <b>after</b> the returned {@code Future} is done: the future
 * completes before closing starts, rather than once it has finished.
 *
 * <pre>{@code
 * FluentFuture<UserName> userName =

  @GwtIncompatible(value = "java.util.regex.Pattern")
  public static Predicate<CharSequence> contains(Pattern pattern) {
    return new ContainsPatternPredicate(new JdkPattern(pattern));
  }

  // End public API, begin private implementation classes.

  // Package private for GWT serialization.
  enum ObjectPredicate implements Predicate<@Nullable Object> {
    /** @see Predicates#alwaysTrue() */
    ALWAYS_TRUE {
      @Override

   *
   * <p>If a task is {@linkplain Thread#interrupt interrupted} while a task is running:
   *
   * <ol>
   *   <li>execution will not stop until the task queue is empty.
   *   <li>tasks will begin execution with the thread marked as not interrupted - any interruption
   *       applies only to the task that was running at the point of interruption.