private final String separator;
    private final int afterEveryChars;

    SeparatedBaseEncoding(BaseEncoding delegate, String separator, int afterEveryChars) {
      this.delegate = checkNotNull(delegate);
      this.separator = checkNotNull(separator);
      this.afterEveryChars = afterEveryChars;
      checkArgument(
          afterEveryChars > 0, "Cannot add a separator after every %s chars", afterEveryChars);