) {
  /** Write [byteCount] bytes from [source] to the file at [pos]. */
  @Throws(IOException::class)
  fun write(
    pos: Long,
    source: Buffer,
    byteCount: Long,
  ) {
    if (byteCount < 0L || byteCount > source.size) {
      throw IndexOutOfBoundsException()
    }
    var mutablePos = pos
    var mutableByteCount = byteCount

    while (mutableByteCount > 0L) {