Ember.subscribe not working (Syntax error)

Ember CLI
1

Dear Members

I am trying to implement Ember.subscribe

TestSubscribe: function(fileId)
{
   Ember.subscribe(fileId, function()
  {
    before: function(){
     //code
   },

  after: function(){
   //code
   },
});
}

This syntax is giving error in browser.

Please tell the correct way to do so, in Ember 2.3