code: function(_hook, _fun) {
        if(this.$$cb && this.$$cb[_hook]) {
          var idx = Utils.indexWhere(this.$$cb[_hook], function(e) { return e === _fun; });
          if(idx !== -1) this.$$cb[_hook].splice(idx, 1);
        }
        return this;
      }
docs: @memberof CommonApi#
  
  @description Unregisters an instance hook registered with `$on`
  
  @param {string} _hook Hook name
  @param {function} _fun Original callback
  @return {CommonApi} self