*     in an {@code int}
   */
  public static char[] concat(char[]... arrays) {
    long length = 0;
    for (char[] array : arrays) {
      length += array.length;
    }
    char[] result = new char[checkNoOverflow(length)];
    int pos = 0;
    for (char[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);
      pos += array.length;
    }
    return result;
  }

   *     in an {@code int}
   */
  public static float[] concat(float[]... arrays) {
    long length = 0;
    for (float[] array : arrays) {
      length += array.length;
    }
    float[] result = new float[checkNoOverflow(length)];
    int pos = 0;
    for (float[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);
      pos += array.length;
    }
    return result;

   *     in an {@code int}
   */
  public static double[] concat(double[]... arrays) {
    long length = 0;
    for (double[] array : arrays) {
      length += array.length;
    }
    double[] result = new double[checkNoOverflow(length)];
    int pos = 0;
    for (double[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);
      pos += array.length;
    }

   *     in an {@code int}
   */
  public static short[] concat(short[]... arrays) {
    long length = 0;
    for (short[] array : arrays) {
      length += array.length;
    }
    short[] result = new short[checkNoOverflow(length)];
    int pos = 0;
    for (short[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);
      pos += array.length;
    }
    return result;

   *     in an {@code int}
   */
  public static short[] concat(short[]... arrays) {
    long length = 0;
    for (short[] array : arrays) {
      length += array.length;
    }
    short[] result = new short[checkNoOverflow(length)];
    int pos = 0;
    for (short[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);
      pos += array.length;
    }
    return result;

   *     in an {@code int}
   */
  public static char[] concat(char[]... arrays) {
    long length = 0;
    for (char[] array : arrays) {
      length += array.length;
    }
    char[] result = new char[checkNoOverflow(length)];
    int pos = 0;
    for (char[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);
      pos += array.length;
    }
    return result;
  }

    return CompactHashSet.create();
  }

  /**
   * Returns a new array of the given length with the same type as a reference array.
   *
   * @param reference any array of the desired type
   * @param length the length of the new array
   */
  /*
   * The new array contains nulls, even if the old array did not. If we wanted to be accurate, we

        this.output = output == null ? null : output.replace("\n", " ");
        Arrays.sort(inputs);

        if (id == 0) {
            // create
            newInputs = inputs;
            newOutput = output;
        }
    }

    /**
     * Returns the array of new input character sequences for update operations.
     *
     * @return array of new input sequences, or null if no updates are pending
     */

   *     in an {@code int}
   */
  public static int[] concat(int[]... arrays) {
    long length = 0;
    for (int[] array : arrays) {
      length += array.length;
    }
    int[] result = new int[checkNoOverflow(length)];
    int pos = 0;
    for (int[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);
      pos += array.length;
    }
    return result;
  }

    return CompactHashSet.create();
  }

  /**
   * Returns a new array of the given length with the same type as a reference array.
   *
   * @param reference any array of the desired type
   * @param length the length of the new array
   */
  /*
   * The new array contains nulls, even if the old array did not. If we wanted to be accurate, we