docs: def serialize(self, method="urlencoded", lev=0, **kwargs):
          """
          Convert this instance to another representation. Which representation 
          is given by the choice of serialization method.
          
          :param method: A serialization method. Presently 'urlencoded', 'json',
              'jwt' and 'dict' is supported.
          :param lev: 
          :param kwargs: Extra key word arguments
          :return: THe content of this message serialized using a chosen method
          """
          return getattr(self, "to_%s" % method)(lev=lev, **kwargs)