You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: main.go
    path of file: ./repos/gocv/cmd/faceblur
    
    the code of the file until where you have to start completion: // What it doe
    
func main() {
	if len(os.Args) < 3 {
		fmt.Println("How to run:\n\tfaceblur [camera ID] [classifier XML file]")
		return
	}

	// parse args
	deviceID := os.Args[1]
	xmlFile := os.Args[2]

	// open webcam
	webcam, err := gocv.OpenVideoCapture(deviceID)
	if err != nil {
		fmt.Printf("error opening video capture device: %v\n", deviceID)
		return
	}
	defer webcam.Close()

	// open display window
	window := gocv.NewWindow("Face Blur")
	defer window.Close()

	// prepare image matrix
	img := gocv.NewMat()
	defer img.Close()

	// load classifier to recognize faces
	classifier := gocv.NewCascadeClassifier()
	defer classifier.Close()

	if !classifier.Load(xmlFile) {
		fmt.Printf("Error reading cascade file: %v\n", xmlFile)
		return
	}

	fmt.Printf("Start reading device: %v\n", deviceID)
	for {
		if ok := webcam.Read(&img); !ok {
			fmt.Printf("Device closed: %v\n", deviceID)
			return
		}
		if img.Empty() {
			continue
		}

		// detect faces
		rects := classifier.DetectMultiScale(img)
		fmt.Printf("found %d faces\n", len(rects))

		// blur each face on the original image
		for _, r := range rects {
			imgFace := img.Region(r)

			// blur face
			gocv.GaussianBlur(imgFace, &imgFace, image.Pt(75, 75), 0, 0, gocv.BorderDefault)
			imgFace.Close()
		}

		// show the image in the window, and wait 1 millisecond
		window.IMShow(img)
		if window.WaitKey(1) >= 0 {
			break
		}
	}
}