unity where to put dontdestroyonload code example

Example 1: dontdestroyonload unity

DontDestroyOnLoad(this.gameObject);

Example 2: unity dontdestroyonload

private void Awake(){
	if(instance == null){
		instance = this;
    	DontDestroyOnLoad(instance);
	}
	else{
		Destroy(gameObject)
	}
}