private final R row;
    private final C column;
    private V value;

    MutableCell(R row, C column, V value) {
      this.row = checkNotNull(row, "row");
      this.column = checkNotNull(column, "column");
      this.value = checkNotNull(value, "value");
    }

    @Override
    public R getRowKey() {
      return row;
    }

    @Override

      Map<Integer, C> row = table.row("foo");
      assertEquals(ImmutableMap.of(1, 'a', 3, 'c'), row);
      table.remove("foo", 3);
      assertEquals(ImmutableMap.of(1, 'a'), row);
      table.remove("foo", 1);
      assertEquals(ImmutableMap.of(), row);
      table.put("foo", 2, cellValue('b'));
      assertEquals(ImmutableMap.of(2, 'b'), row);
      row.clear();
      assertEquals(ImmutableMap.of(), row);

 * Null row keys, columns keys, and values are not supported.
 *
 * <p>Lookups by row key are often faster than lookups by column key, because the data is stored in
 * a {@code Map<R, Map<C, V>>}. A method call like {@code column(columnKey).get(rowKey)} still runs
 * quickly, since the row key is provided. However, {@code column(columnKey).size()} takes longer,

    table.put("b", "b", "x");
    table.put("b", "c", "y");
    table.put("b", "x", "n");
    table.put("a", "a", "d");
    table.row("b").subMap("c", "x").clear();
    assertEquals(table.row("b"), ImmutableMap.of("b", "x", "x", "n"));
    table.row("b").subMap("b", "y").clear();
    assertEquals(table.row("b"), ImmutableMap.of());
    assertFalse(table.backingMap.containsKey("b"));
  }

      Map<Integer, C> row = table.row("foo");
      assertEquals(ImmutableMap.of(1, 'a', 3, 'c'), row);
      table.remove("foo", 3);
      assertEquals(ImmutableMap.of(1, 'a'), row);
      table.remove("foo", 1);
      assertEquals(ImmutableMap.of(), row);
      table.put("foo", 2, cellValue('b'));
      assertEquals(ImmutableMap.of(2, 'b'), row);
      row.clear();
      assertEquals(ImmutableMap.of(), row);

    assertEquals(ImmutableMap.of(1, ImmutableMap.of('a', "blah")), testTable.columnMap());
  }

  public void testRow() {
    assertEquals(ImmutableMap.of(), testTable.row('A'));
    assertEquals(ImmutableMap.of(1, "blah"), testTable.row('a'));
  }

  public void testRowKeySet() {
    assertEquals(ImmutableSet.of('a'), testTable.rowKeySet());
  }

  public void testRowMap() {

    for (ImmutableTable<Character, Integer, String> testInstance : getTestInstances()) {
      assertEquals(ImmutableMap.of(1, "foo", 2, "baz"), testInstance.row('a'));
      assertEquals(ImmutableMap.of(1, "bar"), testInstance.row('b'));
      assertEquals(ImmutableMap.of(), testInstance.row('c'));
    }
  }

  public void testRowKeySet() {
    for (ImmutableTable<Character, Integer, String> testInstance : getTestInstances()) {

  @CheckForNull
  public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
    return delegate().remove(rowKey, columnKey);
  }

  @Override
  public Map<C, V> row(@ParametricNullness R rowKey) {
    return delegate().row(rowKey);
  }

  @Override
  public Set<R> rowKeySet() {
    return delegate().rowKeySet();
  }

  @Override
  public Map<R, Map<C, V>> rowMap() {

    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    assertEquals(ImmutableMap.of(1, 'a', 3, 'c'), table.row("foo"));
  }

  // This test assumes that the implementation does not support null keys.
  public void testRowNull() {
    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    try {
      table.row(null);
      fail();
    } catch (NullPointerException expected) {
    }
  }

    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    assertEquals(ImmutableMap.of(1, 'a', 3, 'c'), table.row("foo"));
  }

  // This test assumes that the implementation does not support null keys.
  public void testRowNull() {
    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    try {
      table.row(null);
      fail();
    } catch (NullPointerException expected) {
    }
  }