result.writeUtf8(string, pos, limit)
      return true
    }

    var pos = pos + 4 // 'xn--'.size.

    // We'd prefer to operate directly on `result` but it doesn't offer insertCodePoint(), only
    // appendCodePoint(). The Punycode algorithm processes code points in increasing code-point
    // order, not in increasing index order.
    val codePoints = mutableListOf<Int>()