private static final class InverseSerializedForm<K, V> implements Serializable {
    private final ImmutableBiMap<K, V> forward;

    InverseSerializedForm(ImmutableBiMap<K, V> forward) {
      this.forward = forward;
    }

    Object readResolve() {
      return forward.inverse();
    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 1;
  }

    private final HashBiMap<K, V> forward;

    Inverse(HashBiMap<K, V> forward) {
      this.forward = forward;
    }

    @Override
    public int size() {
      return forward.size;
    }

    @Override
    public boolean containsKey(@Nullable Object key) {
      return forward.containsValue(key);
    }

    @Override

   * forward to this implementation.
   */
  protected @Nullable Entry<K, V> standardFirstEntry() {
    return Iterables.<@Nullable Entry<K, V>>getFirst(entrySet(), null);
  }

  /**
   * A sensible definition of {@link #firstKey} in terms of {@code firstEntry}. If you override
   * {@code firstEntry}, you may wish to override {@code firstKey} to forward to this
   * implementation.
   */

   * forward to this implementation.
   */
  protected @Nullable Entry<K, V> standardFirstEntry() {
    return Iterables.<@Nullable Entry<K, V>>getFirst(entrySet(), null);
  }

  /**
   * A sensible definition of {@link #firstKey} in terms of {@code firstEntry}. If you override
   * {@code firstEntry}, you may wish to override {@code firstKey} to forward to this
   * implementation.
   */

import org.jspecify.annotations.Nullable;

/**
 * A navigable set which forwards all its method calls to another navigable set. Subclasses should
 * override one or more methods to modify the behavior of the backing set as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingNavigableSet} forward <i>indiscriminately</i>

   * forward to this implementation.
   *
   * @since 7.0
   */
  protected int standardHashCode() {
    return Sets.hashCodeImpl(entrySet());
  }

  /**
   * A sensible definition of {@link #toString} in terms of the {@code iterator} method of {@link
   * #entrySet}. If you override {@link #entrySet}, you may wish to override {@link #toString} to
   * forward to this implementation.
   *

  private final transient ImmutableSortedMultiset<E> forward;

  DescendingImmutableSortedMultiset(ImmutableSortedMultiset<E> forward) {
    this.forward = forward;
  }

  @Override
  public int count(@Nullable Object element) {
    return forward.count(element);
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return forward.lastEntry();
  }

  @Override

/**
 * A sorted multiset which forwards all its method calls to another sorted multiset. Subclasses
 * should override one or more methods to modify the behavior of the backing multiset as desired per
 * the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingSortedMultiset} forward

   * this implementation.
   *
   * @since 7.0
   */
  protected boolean standardEquals(@Nullable Object object) {
    return Sets.equalsImpl(this, object);
  }

  /**
   * A sensible definition of {@link #hashCode} in terms of {@link #iterator}. If you override
   * {@link #iterator}, you may wish to override {@link #equals} to forward to this implementation.
   *
   * @since 7.0

  public void testFrom() {
    Function<String, Integer> forward =
        new Function<String, Integer>() {
          @Override
          public Integer apply(String input) {
            return Integer.parseInt(input);
          }
        };
    Function<Object, String> backward = toStringFunction();

    Converter<String, Number> converter = Converter.<String, Number>from(forward, backward);