implements MapDifference<K, V> {
    final Map<K, V> onlyOnLeft;
    final Map<K, V> onlyOnRight;
    final Map<K, V> onBoth;
    final Map<K, ValueDifference<V>> differences;

    MapDifferenceImpl(
        Map<K, V> onlyOnLeft,
        Map<K, V> onlyOnRight,
        Map<K, V> onBoth,
        Map<K, ValueDifference<V>> differences) {
      this.onlyOnLeft = unmodifiableMap(onlyOnLeft);

     */
    protected Maps(final Map<K, V> map) {
        this.map = map;
    }

    /**
     * {@link Map}にキーと値を追加します。
     *
     * @param key
     *            <code>Map</code>に追加されるキー
     * @param value
     *            <code>Map</code>に追加される値
     * @return このインスタンス自身
     */
    public Maps<K, V> $(final K key, final V value) {
        map.put(key, value);
        return this;

    TreeMap<Integer, Integer> map = Maps.newTreeMap(SOME_COMPARATOR);
    assertEquals(Collections.emptyMap(), map);
    assertSame(SOME_COMPARATOR, map.comparator());
  }

  public void testTreeMapWithInitialMap() {
    SortedMap<Integer, Integer> map = Maps.newTreeMap();
    map.put(5, 10);
    map.put(3, 20);
    map.put(1, 30);
    TreeMap<Integer, Integer> copy = Maps.newTreeMap(map);
    assertEquals(copy, map);

    TreeMap<Integer, Integer> map = Maps.newTreeMap(SOME_COMPARATOR);
    assertEquals(Collections.emptyMap(), map);
    assertSame(SOME_COMPARATOR, map.comparator());
  }

  public void testTreeMapWithInitialMap() {
    SortedMap<Integer, Integer> map = Maps.newTreeMap();
    map.put(5, 10);
    map.put(3, 20);
    map.put(1, 30);
    TreeMap<Integer, Integer> copy = Maps.newTreeMap(map);
    assertEquals(copy, map);

    assertEquals("1", map.remove("a"));
    assertNull(map.remove("b"));
  }

  public void testTransformEqualityOfMapsWithNullValues() {
    Map<String, @Nullable String> underlying = Maps.newHashMap();
    underlying.put("a", null);
    underlying.put("b", "");

    Map<String, Boolean> map =
        Maps.transformValues(
            underlying,

    assertEquals("1", map.remove("a"));
    assertNull(map.remove("b"));
  }

  public void testTransformEqualityOfMapsWithNullValues() {
    Map<String, @Nullable String> underlying = Maps.newHashMap();
    underlying.put("a", null);
    underlying.put("b", "");

    Map<String, Boolean> map =
        Maps.transformValues(
            underlying,

    Map<String, Integer> equalToUnderlying = Maps.newTreeMap();
    equalToUnderlying.putAll(underlying);
    Map<String, Integer> map =
        Maps.transformValues(equalToUnderlying, Functions.<Integer>identity());
    assertMapsEqual(expected, map);

    map =
        Maps.transformValues(
            ImmutableMap.of("a", 1, "b", 2, "c", 3),
            new Function<Integer, Integer>() {

    for (Map<C, V> row : rowMap().values()) {
      if (row.containsValue(value)) {
        return true;
      }
    }
    return false;
  }

  @Override
  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
    Map<C, V> row = Maps.safeGet(rowMap(), rowKey);
    return row != null && Maps.safeContainsKey(row, columnKey);
  }

  @Override

    @Override
    protected Map<AnEnum, String> create(Entry<AnEnum, String>[] entries) {
      Map<AnEnum, String> map = Maps.newHashMap();
      for (Entry<AnEnum, String> entry : entries) {
        map.put(entry.getKey(), entry.getValue());
      }
      return Maps.immutableEnumMap(map);
    }
  }

  @J2ktIncompatible
  @GwtIncompatible // suite

  public void testForMapSerialization() {
    Map<String, Integer> map = Maps.newHashMap();
    map.put("foo", 1);
    map.put("bar", 2);
    Multimap<String, Integer> multimapView = Multimaps.forMap(map);
    SerializableTester.reserializeAndAssert(multimapView);
  }

  public void testForMapRemoveAll() {
    Map<String, Integer> map = Maps.newHashMap();
    map.put("foo", 1);
    map.put("bar", 2);
    map.put("cow", 3);