code: public static byte[] asciiBytes(String value) {
      Preconditions.checkNotNull(value);
      try {
        return value.getBytes("ASCII");
      } catch (UnsupportedEncodingException uee) {
        // won't happen
        throw new RuntimeException("ASCII not found!", uee);
      }
    }
docs: Helper method that transforms provided string into it's byte representation
  using ASCII encoding.
  @param value the string to use
  @return byte array representing ascii encoded value