this.arithmetic = arithmetic;
    }

    @Override
    public int add(int a, int b) {
      return arithmetic.add(a, b);
    }

    @Override
    public int minus(int a, int b) {
      return arithmetic.minus(a, b);
    }

    @Override
    public String toString() {
      return arithmetic.toString();
    }
  }

   * Returns an immutable set containing the given elements, minus duplicates, in the order each was
   * first specified. That is, if multiple elements are {@linkplain Object#equals equal}, all except
   * the first are ignored.
   */
  public static <E> ImmutableSet<E> of(E e1, E e2) {
    return construct(2, e1, e2);
  }

  /**
   * Returns an immutable set containing the given elements, minus duplicates, in the order each was

              return roundCeilingAsDouble;
            }
            roundFloor = toX(roundFloorAsDouble, RoundingMode.FLOOR);
          }

          X deltaToFloor = minus(x, roundFloor);
          X deltaToCeiling = minus(roundCeiling, x);
          int diff = deltaToFloor.compareTo(deltaToCeiling);
          if (diff < 0) { // closer to floor
            return roundFloorAsDouble;

      this.arithmetic = arithmetic;
    }

    @Override
    public int add(int a, int b) {
      return arithmetic.add(a, b);
    }

    @Override
    public int minus(int a, int b) {
      return arithmetic.minus(a, b);
    }

    @Override
    public String toString() {
      return arithmetic.toString();
    }
  }

   * _could_, so we could keep it as it is. Or we could convince ourselves that hash flooding is
   * unlikely in practice there, too.)
   */

  /**
   * Returns an immutable set containing the given elements, minus duplicates, in the order each was
   * first specified. That is, if multiple elements are {@linkplain Object#equals equal}, all except
   * the first are ignored.
   */
  public static <E> ImmutableSet<E> of(E e1, E e2) {

  @Override
  protected Map<String, Integer> makePopulatedMap() {
    return ImmutableMap.of("one", 1);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return -1;
  }

  @Override
  protected SortedMap<String, Integer> makePopulatedMap() {
    return ImmutableSortedMap.of("one", 1);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return -1;
  }

  protected Map<String, Integer> makePopulatedMap() {
    return SerializableTester.reserialize(ImmutableMap.of("one", 1, "two", 2, "three", 3));
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return -1;
  }

  @Override
  protected Map<String, Integer> makePopulatedMap() {
    return ImmutableMap.of("one", 1);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return -1;
  }

  }

  @Override
  protected Map<String, Integer> makePopulatedMap() {
    return ImmutableMap.of("one", 1, "two", 2, "three", 3);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return -1;
  }