code: def conf(self, key=None, defval=None):
          '''return YunpianConf if key=None, else return value in YunpianConf'''
          if key is None:
              return self._ypconf
          val = self._ypconf.conf(key)
          return defval if val is None else vaf conf(self, key=None, defval=None):
          '''return YunpianConf if key=None, else return value in YunpianConf'''
          if key is None:
              return self._ypconf
          val = self._ypconf.conf(key)
          return defval if val is None else val
docs: return YunpianConf if key=None, else return value in YunpianConf