assertThat(UnsignedLongs.parseUnsignedLong("18446744073709551615"))
        .isEqualTo(0xffffffffffffffffL);
    assertThat(UnsignedLongs.parseUnsignedLong("9223372036854775807"))
        .isEqualTo(0x7fffffffffffffffL);
    assertThat(UnsignedLongs.parseUnsignedLong("18382112080831834642"))
        .isEqualTo(0xff1a618b7f65ea12L);
    assertThat(UnsignedLongs.parseUnsignedLong("6504067269626408013"))

   *
   * <p><b>Java 8+ users:</b> use {@link Long#parseUnsignedLong(String)} instead.
   *
   * @throws NumberFormatException if the string does not contain a valid unsigned {@code long}
   *     value
   * @throws NullPointerException if {@code string} is null (in contrast to {@link
   *     Long#parseLong(String)})
   */
  @CanIgnoreReturnValue
  public static long parseUnsignedLong(String string) {