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: config.go
    path of file: ./repos/googlekeepclone
    
    the code of the file until where you have to start completion: package googlekeepclone

import (
	"fmt"
	"log"
	"net/url"
	"os"
)

// AppConfig holds the configuration for the application
type AppConfig struct {
	IsProd            bool
	AppHost           *url.URL
	DBFile            string
	StaticDir         string
	CookieStoreKey    string
	SessionStoreKey   string
	SessionCookieName string
}

// DefaultAppConfig creates an instance of AppConfig and populates with default/environment values
func DefaultAppConfig() *AppConfig {
	production := os.Getenv("PRODUCTION")

	host := os.Getenv("HOST")
	if host == "" {
		log.Fatal("The environment variable HOST doesn't exist")
	}

	port := os.Getenv("PORT")
	if port == "" {
		log.Fatal("The environment variable PORT doesn't exist")
	}

	appHost, err := url.Parse(fmt.Sprintf("%s:%s", host, port))
	if err != nil {
		log.Fatal("The environmental variable HOST or PORT is malformed")
	}

	cookieStoreKey := os.Getenv("COOKIE_STORE_KEY")
	if cookieStoreKey == "" {
		log.Fatal("The environment variable COOKIE_STORE_KEY doesn't exist")
	}

	sessionStoreKey := os.Getenv("SESSION_STORE_K
    
func DefaultAppConfig() *AppConfig {
	production := os.Getenv("PRODUCTION")

	host := os.Getenv("HOST")
	if host == "" {
		log.Fatal("The environment variable HOST doesn't exist")
	}

	port := os.Getenv("PORT")
	if port == "" {
		log.Fatal("The environment variable PORT doesn't exist")
	}

	appHost, err := url.Parse(fmt.Sprintf("%s:%s", host, port))
	if err != nil {
		log.Fatal("The environmental variable HOST or PORT is malformed")
	}

	cookieStoreKey := os.Getenv("COOKIE_STORE_KEY")
	if cookieStoreKey == "" {
		log.Fatal("The environment variable COOKIE_STORE_KEY doesn't exist")
	}

	sessionStoreKey := os.Getenv("SESSION_STORE_KEY")
	if sessionStoreKey == "" {
		log.Fatal("The environment variable SESSION_STORE_KEY doesn't exist")
	}

	dbFile := os.Getenv("DB_FILE")
	if dbFile == "" {
		dbFile = "keepclone.db"
	}

	staticDir := os.Getenv("STATIC_DIR")
	if staticDir == "" {
		staticDir = "./web/build/"
	}

	return &AppConfig{
		IsProd:            production != "",
		AppHost:           appHost,
		DBFile:            dbFile,
		StaticDir:         staticDir,
		CookieStoreKey:    cookieStoreKey,
		SessionStoreKey:   sessionStoreKey,
		SessionCookieName: "gkc_session",
	}
}