* Immutable empty instances are returned for collection types; {@code ""} for string; {@code 0} for
 * number types; reasonable default instance for other stateless types. For mutable types, a fresh
 * instance is created each time {@code get()} is called.
 *
 * @author Kevin Bourrillion
 * @author Ben Yu
 * @since 12.0
 */
@GwtIncompatible
@J2ktIncompatible

 * Immutable empty instances are returned for collection types; {@code ""} for string; {@code 0} for
 * number types; reasonable default instance for other stateless types. For mutable types, a fresh
 * instance is created each time {@code get()} is called.
 *
 * @author Kevin Bourrillion
 * @author Ben Yu
 * @since 12.0
 */
@GwtIncompatible
@J2ktIncompatible

import java.util.Map;
import java.util.Set;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A mutable type-to-instance map. See also {@link ImmutableTypeToInstanceMap}.
 *
 * @author Ben Yu
 * @since 13.0
 */
@ElementTypesAreNonnullByDefault
public final class MutableTypeToInstanceMap<B extends @Nullable Object>

   * As such, this field must be cleared before every map mutation.
   *
   * Note about volatile: volatile doesn't make it safe to read from a mutable graph in one thread
   * while writing to it in another. All it does is help with _reading_ from multiple threads
   * concurrently. For more information, see AbstractNetworkTest.concurrentIteration.
   */

   * snapshot of the state and therefore it can be used to answer simple queries without needing to
   * grab a lock.
   */
  // @Immutable except that Throwable is mutable (initCause(), setStackTrace(), mutable subclasses).
  private static final class StateSnapshot {
    /**
     * The internal state, which equals external state unless shutdownWhenStartupFinishes is true.
     */
    final State state;

  // A cancellation manager to use if the caller does not provide one. When ops
  // are executed asynchronously this must outlive the queued op, so it can't be
  // function-local to Execute.
  mutable std::unique_ptr<CancellationManager> default_cancellation_manager_;
};

// Contains a tuple of tensors, one on each of the `underlying_devices_` of the
// ParallelDevice.
class ParallelTensor {
 public:

   * graphBuilder.incidentEdgeOrder(ElementOrder.stable())}.
   *
   * <h3>In combination with {@code incidentEdgeOrder}</h3>
   *
   * <p>{@code incidentEdgeOrder(ElementOrder.stable())} guarantees the ordering of the returned
   * collections of the following methods:
   *
   * <ul>
   *   <li>For {@link Graph} and {@link ValueGraph}:
   *       <ul>
   *         <li>{@code edges()}: Stable order

   * graphBuilder.incidentEdgeOrder(ElementOrder.stable())}.
   *
   * <h3>In combination with {@code incidentEdgeOrder}</h3>
   *
   * <p>{@code incidentEdgeOrder(ElementOrder.stable())} guarantees the ordering of the returned
   * collections of the following methods:
   *
   * <ul>
   *   <li>For {@link Graph} and {@link ValueGraph}:
   *       <ul>
   *         <li>{@code edges()}: Stable order

 * @param <E> Edge parameter type
 */
@ElementTypesAreNonnullByDefault
final class StandardMutableNetwork<N, E> extends StandardNetwork<N, E>
    implements MutableNetwork<N, E> {

  /** Constructs a mutable graph with the properties specified in {@code builder}. */
  StandardMutableNetwork(NetworkBuilder<? super N, ? super E> builder) {
    super(builder);
  }

  @Override
  @CanIgnoreReturnValue

 * if key or value objects already present in the multimap change in a manner that affects
 * {@code equals} comparisons. Use caution if mutable objects are used as keys or values in a {@code
 * SetMultimap}.
 *
 * <p><b>Warning:</b> Do not modify either a key <i>or a value</i> of a {@code SetMultimap} in a way