return AnyValue(
            tagClass = header.tagClass,
            tag = header.tag,
            constructed = header.constructed,
            length = header.length,
            bytes = bytes,
          )
        }
      }

      override fun toDer(
        writer: DerWriter,
        value: AnyValue,
      ) {
        writer.write("ANY", value.tagClass, value.tag) {

      name = "test",
      tagClass = DerHeader.TAG_CLASS_UNIVERSAL,
      tag = 16L,
    ) {
      derWriter.write(
        name = "test",
        tagClass = DerHeader.TAG_CLASS_UNIVERSAL,
        tag = 21L,
      ) {
        derWriter.writeOctetString("Smith".encodeUtf8())
      }

      derWriter.write(
        name = "test",
        tagClass = DerHeader.TAG_CLASS_UNIVERSAL,
        tag = 1L,

    // We've exhausted the source stream.
    if (limit == -1L && source.exhausted()) return END_OF_DATA

    // Read the tag.
    val tagAndClass = source.readByte().toInt() and 0xff
    val tagClass = tagAndClass and 0b1100_0000
    val constructed = (tagAndClass and 0b0010_0000) == 0b0010_0000
    val tag =
      when (val tag0 = tagAndClass and 0b0001_1111) {
        0b0001_1111 -> readVariableLengthLong()