func connectToMongoDB() {...}

pt-3.main.go

func connectToMongoDB() {
	if client != nil {
		return
	}
	var connectionError error
	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
	client, connectionError = mongo.Connect(ctx, options.Client().ApplyURI(mongoURI))
	fmt.Printf("%+v", client)
	collection = client.Database(dbName).Collection(col) // <--- since I'm only using one collection this can be global
	defer cancel()

	if connectionError != nil {
		fmt.Printf("this is an eror %+v", connectionError)
	}
}