block = (bytes[i++] & 0xff) << 16 | (bytes[i++] & 0xff) << 8 | bytes[i++] & 0xff;
            buffer.append(ALPHABET.charAt(block >>> 18));
            buffer.append(ALPHABET.charAt(block >>> 12 & 0x3f));
            buffer.append(ALPHABET.charAt(block >>> 6 & 0x3f));
            buffer.append(ALPHABET.charAt(block & 0x3f));
        }
        if (remainder == 0) {
            return buffer.toString();
        }

   */
  @Deprecated @J2ktIncompatible @GwtIncompatible // Charset not supported by GWT
  public static final Charset US_ASCII = StandardCharsets.US_ASCII;

  /**
   * ISO-8859-1: ISO Latin Alphabet Number 1 (ISO-LATIN-1).
   *
   * @deprecated Use {@link StandardCharsets#ISO_8859_1} instead.
   */
  @Deprecated public static final Charset ISO_8859_1 = StandardCharsets.ISO_8859_1;

  /**

  }

  /**
   * Determines whether a character is a BMP letter according to {@linkplain
   * Character#isLetter(char) Java's definition}. If you only care to match letters of the Latin
   * alphabet, you can use {@code inRange('a', 'z').or(inRange('A', 'Z'))}.
   *
   * @deprecated Most letters are supplementary characters; see the class documentation.
   * @since 19.0 (since 1.0 as constant {@code JAVA_LETTER})
   */

		panic("Negative length passed to DummyDataGen!")
	}
	if skipOffset < 0 {
		panic("Negative rotations are not allowed")
	}

	skipOffset %= int64(len(alphabets))
	const multiply = 100
	as := bytes.Repeat(alphabets, multiply)
	b := as[skipOffset : skipOffset+int64(len(alphabets)*(multiply-1))]
	return &DummyDataGen{
		length: totalLength,
		b:      b,
	}
}

func (d *DummyDataGen) Read(b []byte) (n int, err error) {