}
  }

  public void testPut() {
    assertNull(table.put("foo", 1, cellValue('a')));
    assertNull(table.put("bar", 1, cellValue('b')));
    assertNull(table.put("foo", 3, cellValue('c')));
    assertEquals((Character) 'a', table.put("foo", 1, cellValue('d')));
    assertEquals((Character) 'd', table.get("foo", 1));
    assertEquals((Character) 'b', table.get("bar", 1));

    }
  }

  public void testPut() {
    assertNull(table.put("foo", 1, cellValue('a')));
    assertNull(table.put("bar", 1, cellValue('b')));
    assertNull(table.put("foo", 3, cellValue('c')));
    assertEquals((Character) 'a', table.put("foo", 1, cellValue('d')));
    assertEquals((Character) 'd', table.get("foo", 1));
    assertEquals((Character) 'b', table.get("bar", 1));

    }

    Object readResolve() {
      if (cellValues.length == 0) {
        return of();
      }
      if (cellValues.length == 1) {
        return of(rowKeys[0], columnKeys[0], cellValues[0]);
      }
      ImmutableList.Builder<Cell<Object, Object, Object>> cellListBuilder =
          new ImmutableList.Builder<>(cellValues.length);
      for (int i = 0; i < cellValues.length; i++) {
        cellListBuilder.add(