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/iris/_examples/url-shortener
    
    the code of the file until where you have to start completion: // Package main shows how you can create a simple URL Shortener.
//
// Article: https://medium.com/@kataras/a
    
func main() {
	// assign a variable to the DB so we can use its features later.
	db := NewDB("shortener.db")
	// Pass that db to our app, in order to be able to test the whole app with a different database later on.
	app := newApp(db)

	// release the "db" connection when server goes off.
	iris.RegisterOnInterrupt(db.Close)

	app.Listen(":8080")
}