}

  private static CharMatcher.IsEither isEither(char c1, char c2) {
    return new CharMatcher.IsEither(c1, c2);
  }

  /** Implementation of {@link #anyOf(CharSequence)} for exactly two characters. */
  private static final class IsEither extends FastMatcher {

    private final char match1;
    private final char match2;

    IsEither(char match1, char match2) {
      this.match1 = match1;

        << "Mismatch in expected values at (zero-based) index " << i;
  }
}

void CheckRemoteMatMulExecutesOK(TFE_Context* ctx,
                                 const char* remote_device_name,
                                 const char* local_device_name) {
  TF_Status* status = TF_NewStatus();
  TFE_TensorHandle* h0_task0 = TestMatrixTensorHandle(ctx);

  TFE_Op* matmul = MatMulOp(ctx, h0_task0, h0_task0);

     * @return a hexadecimal string representation of the value, padded to the specified size
     */
    public static String toHexString(final int val, final int size) {
        final char[] c = new char[size];
        toHexChars(val, c, 0, size);
        return new String(c);
    }

    /**
     * Converts a long value to a hexadecimal string representation with specified padding.
     *

  }

  static void checkExactMatches(CharMatcher m, char[] chars) {
    Set<Character> positive = Sets.newHashSetWithExpectedSize(chars.length);
    for (char c : chars) {
      positive.add(c);
    }
    for (int c = 0; c <= Character.MAX_VALUE; c++) {
      assertFalse(positive.contains(Character.valueOf((char) c)) ^ m.matches((char) c));
    }
  }

  static char[] randomChars(Random rand, int size) {

    /**
     * Performs constant-time comparison of two char arrays to prevent timing attacks.
     * This method always compares the full length of both arrays, regardless of when
     * differences are found, making the execution time independent of the position
     * of differing characters.
     *
     * @param a first char array to compare
     * @param b second char array to compare
     * @return true if arrays are equal, false otherwise

   */
  @Override
  protected final char @Nullable [] escape(char c) {
    if (c < replacementsLength) {
      char[] chars = replacements[c];
      if (chars != null) {
        return chars;
      }
    }
    if (c >= safeMin && c <= safeMax) {
      return null;
    }
    return escapeUnsafe(c);
  }

  /**

   */
  private static char[] growBuffer(char[] dest, int index, int size) {
    if (size < 0) { // overflow - should be OutOfMemoryError but GWT/j2cl don't support it
      throw new AssertionError("Cannot increase internal buffer any further");
    }
    char[] copy = new char[size];
    if (index > 0) {
      System.arraycopy(dest, 0, copy, 0, index);
    }

      int h1 = seed;
      int i = 0;
      int len = 0;

      // This loop optimizes for pure ASCII.
      while (i + 4 <= utf16Length) {
        char c0 = input.charAt(i);
        char c1 = input.charAt(i + 1);
        char c2 = input.charAt(i + 2);
        char c3 = input.charAt(i + 3);
        if (c0 < 0x80 && c1 < 0x80 && c2 < 0x80 && c3 < 0x80) {
          int k1 = c0 | (c1 << 8) | (c2 << 16) | (c3 << 24);

      chars.add(randomNonAlpha());
    }
    Collections.shuffle(chars, random);
    char[] array = Chars.toArray(chars);
    this.testString = new String(array);
  }

  private char randomAlpha() {
    return ALPHA.charAt(random.nextInt(ALPHA.length()));
  }

  private char randomNonAlpha() {
    return NONALPHA.charAt(random.nextInt(NONALPHA.length()));
  }

  @Benchmark

        if (length == 0) {
            return;
        }

        final int s = length % 16;
        final int r = s == 0 ? length / 16 : length / 16 + 1;
        final char[] c = new char[r * (74 + NL_LENGTH)];
        final char[] d = new char[16];
        int i;
        int si = 0;
        int ci = 0;

        do {
            toHexChars(si, c, ci, 5);
            ci += 5;
            c[ci] = ':';