Unable to Call Instantiate in Class Member Function

Hi!

The following javascript is attached to a gameObject.

 var instance : GameObject;
 
 class eg_class        {    
     function eg_func(){    
         var thePrefab : GameObject;
            instance = Instantiate(thePrefab);
     }
 }

Error,

Unknown identifier: 'instance'. Unknown identifier: 'Instantiate'.

Questions, 1) Why is it that "instance" cannot be accessed within a class? Isn't it supposed to be a public variable?
2) "Instantiate" function works in Start()/Update() root functions. Is there a way to make it work from within member functions?

Thanks in advance!