/**
   * Returns the empty bimap.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  // Casting to any type is safe because the set will never hold any elements.
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableBiMap<K, V> of() {
    return (ImmutableBiMap<K, V>) RegularImmutableBiMap.EMPTY;
  }

  /** Returns an immutable bimap containing a single entry. */

      throw new UnsupportedOperationException();
    }

    @SuppressWarnings("unchecked")
    @Override
    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
      return get((K) key).remove(value);
    }

    @SuppressWarnings("unchecked")
    @Override
    public Collection<V2> removeAll(@CheckForNull Object key) {

   * code.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  // Casting to any type is safe because the list will never hold any elements.
  @SuppressWarnings("unchecked")
  public static <E> ImmutableList<E> of() {
    return (ImmutableList<E>) EMPTY;
  }

  /**
   * Returns an immutable list containing a single element. This list behaves and performs

  /**
   * Returns the empty multimap.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  // Casting is safe because the multimap will never hold any elements.
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableListMultimap<K, V> of() {
    return (ImmutableListMultimap<K, V>) EmptyImmutableListMultimap.INSTANCE;
  }

  /** Returns an immutable multimap containing a single entry. */

      public Object apply(Entry<?, ?> entry) {
        return entry.getValue();
      }
    };
  }

  @SuppressWarnings("unchecked")
  static <K extends @Nullable Object> Function<Entry<K, ?>, K> keyFunction() {
    return (Function) EntryFunction.KEY;
  }

  @SuppressWarnings("unchecked")
  static <V extends @Nullable Object> Function<Entry<?, V>, V> valueFunction() {
    return (Function) EntryFunction.VALUE;
  }

  }

  /**
   * Returns the empty immutable multiset.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  @SuppressWarnings("unchecked") // all supported methods are covariant
  public static <E> ImmutableMultiset<E> of() {
    return (ImmutableMultiset<E>) RegularImmutableMultiset.EMPTY;
  }

  /**

      @Override
      public <S extends Set<E>> S copyInto(S set) {
        set.addAll(set1);
        set.addAll(set2);
        return set;
      }

      @Override
      @SuppressWarnings({"nullness", "unchecked"}) // see supertype
      public ImmutableSet<@NonNull E> immutableCopy() {
        ImmutableSet.Builder<@NonNull E> builder =
            new ImmutableSet.Builder<@NonNull E>()

  }

  /**
   * Returns the empty immutable sorted multiset.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  @SuppressWarnings("unchecked")
  public static <E> ImmutableSortedMultiset<E> of() {
    return (ImmutableSortedMultiset) RegularImmutableSortedMultiset.NATURAL_EMPTY_MULTISET;
  }