13. 同期版 TcpClient client = // Accept部分は省略 Stream stream = client.GetStream(); while (true) { var buf = new buf[5]; stream.Read(buf, 0, buf.Length); stream.Write(buf, 0, buf.Length); } 15. 同期版（改） static void ReadFully(this Stream stream, byte[] buf) { var readBytes = 0; while (readBytes != buf.Length) { var n = stream.Read(buf, readBytes, buf.Length - readBytes); if (n == 0) throw new Exception("ho