* integrals).
   *
   * Note well that if, for this function, we chose a horizontal line, at height of exactly (1/QPS),
   * then the effect of the function is non-existent: we serve storedPermits at exactly the same
   * cost as fresh ones (1/QPS is the cost for each). We use this trick later.
   *
   * If we pick a function that goes /below/ that horizontal line, it means that we reduce the area

   */
  public abstract V load(K key) throws Exception;

  /**
   * Computes or retrieves a replacement value corresponding to an already-cached {@code key}. This
   * method is called when an existing cache entry is refreshed by {@link
   * CacheBuilder#refreshAfterWrite}, or through a call to {@link LoadingCache#refresh}.
   *
   * <p>This implementation synchronously delegates to {@link #load}. It is recommended that it be

 *     constructed based on an existing {@code Network} using {@link #from(Network)}.
 * @param <E> The most general edge type this builder will support. This is normally {@code Object}
 *     unless it is constrained by using a method like {@link #edgeOrder}, or the builder is
 *     constructed based on an existing {@code Network} using {@link #from(Network)}.
 * @since 20.0
 */
@Beta

      Class<E> clazz) {
    Map<E, LockGraphNode> existing = (Map<E, LockGraphNode>) lockGraphNodesPerType.get(clazz);
    if (existing != null) {
      return existing;
    }
    Map<E, LockGraphNode> created = createNodes(clazz);
    existing = (Map<E, LockGraphNode>) lockGraphNodesPerType.putIfAbsent(clazz, created);
    return MoreObjects.firstNonNull(existing, created);
  }

  /**

  @Override
  public SortedSet<V> removeAll(@CheckForNull Object key) {
    return (SortedSet<V>) super.removeAll(key);
  }

  /**
   * Stores a collection of values with the same key, replacing any existing values for that key.
   * The returned collection is immutable.
   *
   * <p>Because a {@code SortedSetMultimap} has unique sorted values for a given key, this method

  @Override
  public SortedSet<V> removeAll(@CheckForNull Object key) {
    return (SortedSet<V>) super.removeAll(key);
  }

  /**
   * Stores a collection of values with the same key, replacing any existing values for that key.
   * The returned collection is immutable.
   *
   * <p>Because a {@code SortedSetMultimap} has unique sorted values for a given key, this method

 *   <li>{@code weakValues}: sets {@link CacheBuilder#weakValues}.
 *   <li>{@code recordStats}: sets {@link CacheBuilder#recordStats}.
 * </ul>
 *
 * <p>The set of supported keys will grow as {@code CacheBuilder} evolves, but existing keys will
 * never be removed.
 *
 * <p>Durations are represented by an integer, followed by one of "d", "h", "m", or "s",
 * representing days, hours, minutes, or seconds respectively. (There is currently no syntax to

 * <h3>Extension</h3>
 *
 * If you want a class like {@code FluentFuture} but with extra methods, we recommend declaring your
 * own subclass of {@link ListenableFuture}, complete with a method like {@link #from} to adapt an
 * existing {@code ListenableFuture}, implemented atop a {@link ForwardingListenableFuture} that
 * forwards to that future and adds the desired methods.
 *
 * @since 23.0
 */

   */
  @CanIgnoreReturnValue
  boolean putAll(Multimap<? extends K, ? extends V> multimap);

  /**
   * Stores a collection of values with the same key, replacing any existing values for that key.
   *
   * <p>If {@code values} is empty, this is equivalent to {@link #removeAll(Object) removeAll(key)}.
   *

 * associated with a key and then add the key back to the multimap, that key will come last in the
 * key iteration order.
 *
 * <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
 * existing key-value pair has no effect.
 *
 * <p>Keys and values may be null. All optional multimap methods are supported, and all returned
 * views are modifiable.
 *