*
   * If this does write a value, it will write a tag and a length and a full value.
   */
  fun toDer(
    writer: DerWriter,
    value: T,
  )

  fun toDer(value: T): ByteString {
    val buffer = Buffer()
    val writer = DerWriter(buffer)
    toDer(writer, value)
    return buffer.readByteString()
  }

  /**