/**
   * Adds {@code node} if it is not already present.
   *
   * <p><b>Nodes must be unique</b>, just as {@code Map} keys must be. They must also be non-null.
   *
   * @return {@code true} if the graph was modified as a result of this call
   */
  @CanIgnoreReturnValue
  boolean addNode(N node);

  /**
   * Adds an edge connecting {@code nodeU} to {@code nodeV} if one is not already present.
   *

   * @throws IllegalStateException if an initial capacity was already set
   */
  @CanIgnoreReturnValue
  public MapMaker initialCapacity(int initialCapacity) {
    checkState(
        this.initialCapacity == UNSET_INT,
        "initial capacity was already set to %s",
        this.initialCapacity);
    checkArgument(initialCapacity >= 0);

errors.login.failure = Inloggen mislukt.
errors.app.illegal.transition = Illegale overgang. Probeer het opnieuw.
errors.app.db.already.deleted = Mogelijk is het al verwijderd door een ander proces. Probeer de bewerking opnieuw.
errors.app.db.already.updated = Mogelijk is het al bijgewerkt door een ander proces. Probeer de bewerking opnieuw.
errors.app.db.already.exists = Gegevens bestaan al. Probeer de bewerking opnieuw.

errors.login.failure = Ошибка входа.
errors.app.illegal.transition = Недопустимый переход. Пожалуйста, попробуйте еще раз.
errors.app.db.already.deleted = Возможно, он был удален другим процессом. Пожалуйста, попробуйте еще раз.
errors.app.db.already.updated = Возможно, он был обновлен другим процессом. Пожалуйста, попробуйте еще раз.
errors.app.db.already.exists = Данные уже существуют. Пожалуйста, попробуйте еще раз.

      "Cannot call source()/target() on a EndpointPair from an undirected graph. Consider calling "
          + "adjacentNode(node) if you already have a node, or nodeU()/nodeV() if you don't.";
  static final String EDGE_ALREADY_EXISTS = "Edge %s already exists in the graph.";
  static final String ENDPOINTS_MISMATCH =
      "Mismatch: endpoints' ordering is not compatible with directionality of the graph";

    // If the task is already scheduled, take the earlier of the two times.
    val existingIndex = futureTasks.indexOf(task)
    if (existingIndex != -1) {
      if (task.nextExecuteNanoTime <= executeNanoTime) {
        taskRunner.logger.taskLog(task, this) { "already scheduled" }
        return false
      }
      futureTasks.removeAt(existingIndex) // Already scheduled later: reschedule below!
    }

errors.login.failure = Accesso fallito.
errors.app.illegal.transition = Transizione illegale. Riprova.
errors.app.db.already.deleted = Potrebbe essere stato eliminato da un altro processo. Riprova l'operazione.
errors.app.db.already.updated = Potrebbe essere stato aggiornato da un altro processo. Riprova l'operazione.
errors.app.db.already.exists = I dati esistono già. Riprova l'operazione.

  - Fixing or improving documentation.
  - Improvements to Maven configuration.

Guidelines for any code contributions:

  1. Any significant changes should be accompanied by tests. The project already
     has good test coverage, so look at some existing tests if you're unsure
     how to go about it.
  2. All contributions must be licensed Apache 2.0 and all files must have a

      this.mutableValueGraph =
          graphBuilder.copy().incidentEdgeOrder(ElementOrder.<N>stable()).build();
    }

    /**
     * Adds {@code node} if it is not already present.
     *
     * <p><b>Nodes must be unique</b>, just as {@code Map} keys must be. They must also be non-null.
     *
     * @return this {@code Builder} object
     */
    @CanIgnoreReturnValue

    }
  }

  /**
   * Returns an immediately-executable task for the calling thread to execute, sleeping as necessary
   * until one is ready. If there are no ready queues, or if other threads have everything under
   * control this will return null. If there is more than a single task ready to execute immediately
   * this will start another thread to handle that work.
   */
  fun awaitTaskToRun(): Task? {
    assertLockHeld()