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/find-circles
    
    the code of the file until where you have to start completion: // What it does:
//
// This example shows how to find circles in an image using Hough transform.
//
// How to run:
//
// 		go run ./cmd/find-circles/main.go ./images/circles.jpg
//

package main

import (
	"fmt"
	"image"
	"image/color"
	"os"

	"gocv.io/x/gocv"
)

func main() {
	if len(os.Args) < 2 {
		fmt.Println("How to run:\n\tfind-circles [imgfile]")
		return
	}

	filename := os.Args[1]

	window := gocv.NewWindow("detected circles")
	defer window.Close()

	img := gocv.IMRead(filename, gocv.IMReadGrayScale)
	defer img.Close()

	gocv.MedianB
    
func main() {
	if len(os.Args) < 2 {
		fmt.Println("How to run:\n\tfind-circles [imgfile]")
		return
	}

	filename := os.Args[1]

	window := gocv.NewWindow("detected circles")
	defer window.Close()

	img := gocv.IMRead(filename, gocv.IMReadGrayScale)
	defer img.Close()

	gocv.MedianBlur(img, &img, 5)

	cimg := gocv.NewMat()
	defer cimg.Close()

	gocv.CvtColor(img, &cimg, gocv.ColorGrayToBGR)

	circles := gocv.NewMat()
	defer circles.Close()

	gocv.HoughCirclesWithParams(
		img,
		&circles,
		gocv.HoughGradient,
		1,                     // dp
		float64(img.Rows()/8), // minDist
		75,                    // param1
		20,                    // param2
		10,                    // minRadius
		0,                     // maxRadius
	)

	blue := color.RGBA{0, 0, 255, 0}
	red := color.RGBA{255, 0, 0, 0}

	for i := 0; i < circles.Cols(); i++ {
		v := circles.GetVecfAt(0, i)
		// if circles are found
		if len(v) > 2 {
			x := int(v[0])
			y := int(v[1])
			r := int(v[2])

			gocv.Circle(&cimg, image.Pt(x, y), r, blue, 2)
			gocv.Circle(&cimg, image.Pt(x, y), 2, red, 3)
		}
	}

	for {
		window.IMShow(cimg)

		if window.WaitKey(10) >= 0 {
			break
		}
	}
}