nl_tokens: feature flag控制类，提供接口给模板调用，判断某个feature是否开启
pl_tokens: function ( option , req , res ) { this . params = { 'req' : req , 'res' : res } ; this . option = <mask> ; this . features = { } ; //feature实例配置列表 this . logger = Logger . getLogger ( ) ; }