assertThat(Doubles.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Doubles.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Doubles.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Doubles.concat(ARRAY1, ARRAY1, ARRAY1))
        .isEqualTo(new double[] {(double) 1, (double) 1, (double) 1});
    assertThat(Doubles.concat(ARRAY1, ARRAY234))

    assertThat(Floats.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Floats.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Floats.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Floats.concat(ARRAY1, ARRAY1, ARRAY1))
        .isEqualTo(new float[] {(float) 1, (float) 1, (float) 1});
    assertThat(Floats.concat(ARRAY1, ARRAY234))

    assertThat(Ints.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Ints.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Ints.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Ints.concat(ARRAY1, ARRAY1, ARRAY1))
        .isEqualTo(new int[] {(int) 1, (int) 1, (int) 1});
    assertThat(Ints.concat(ARRAY1, ARRAY234))

    assertThat(Chars.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Chars.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Chars.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Chars.concat(ARRAY1, ARRAY1, ARRAY1))
        .isEqualTo(new char[] {(char) 1, (char) 1, (char) 1});
    assertThat(Chars.concat(ARRAY1, ARRAY234))

  void Init(const Element* array, size_t a_size, RelationToSource relation) {
    if (relation == kReference) {
      array_ = array;
    } else {
      Element* const copy = new Element[a_size];
      CopyArray(array, a_size, copy);
      array_ = copy;
    }
    size_ = a_size;
    relation_to_source_ = relation;
  }

  const Element* array_;
  size_t size_;

var byteType = typ((byte)(0))
var ptrType = typ((*byte)(nil))

// Arrays of pointers. There are two size thresholds.
// Bit masks are chunked in groups of 120 pointers.
// Array types with >16384 pointers have a GC program instead of a bitmask.
var smallPtrType = reflect.ArrayOf(100, ptrType)
var mediumPtrType = reflect.ArrayOf(1000, ptrType)
var bigPtrType = reflect.ArrayOf(16385, ptrType)

      System.arraycopy(values.array, values.start, array, count, values.length());
      count += values.length();
      return this;
    }

    private void ensureRoomFor(int numberToAdd) {
      int newCount = count + numberToAdd; // TODO(kevinb): check overflow now?
      if (newCount > array.length) {
        array = Arrays.copyOf(array, expandedCapacity(array.length, newCount));
      }
    }

      System.arraycopy(values.array, values.start, array, count, values.length());
      count += values.length();
      return this;
    }

    private void ensureRoomFor(int numberToAdd) {
      int newCount = count + numberToAdd; // TODO(kevinb): check overflow now?
      if (newCount > array.length) {
        array = Arrays.copyOf(array, expandedCapacity(array.length, newCount));
      }
    }

      System.arraycopy(values.array, values.start, array, count, values.length());
      count += values.length();
      return this;
    }

    private void ensureRoomFor(int numberToAdd) {
      int newCount = count + numberToAdd; // TODO(kevinb): check overflow now?
      if (newCount > array.length) {
        array = Arrays.copyOf(array, expandedCapacity(array.length, newCount));
      }
    }

      System.arraycopy(values.array, values.start, array, count, values.length());
      count += values.length();
      return this;
    }

    private void ensureRoomFor(int numberToAdd) {
      int newCount = count + numberToAdd; // TODO(kevinb): check overflow now?
      if (newCount > array.length) {
        array = Arrays.copyOf(array, expandedCapacity(array.length, newCount));
      }
    }