code: function(key, defaultValue){
              if($ExpressSESSION.session.store[key]){
                  return $ExpressSESSION.session.store[key];
              }
              if(defaultValue) return defaultValue;
              else throw new Error('index '+key+' not exists in session');
          }
docs: Push A Value Onto An Array Or Object Session Value push : function(keys, value){  }, Retrieving An Item Or Returning A Default Value