code: function logout(type, successCallback, errorCallback) {
  
      if(type && Utils.isString(type)){
  
        if(type === 'facebook') {
          return _logoutFacebook.call(this, successCallback, errorCallback);
  
        } else if(type === 'evrythng') {
          return _logoutEvrythng.call(this, successCallback, errorCallback);
        }
  
      }else{
        return _logoutEvrythng.call(this, type, successCallback);
      }
  
    }
docs: **As a good practice, if you log into an app with Facebook, also log out with Facebook. This allows app users to switch Facebook accounts.**