code: def json_dumps(cls, obj, **kwargs):
          
          if 'cls' not in kwargs:
              kwargs['cls'] = cls.json_encoder
          return json.dumps(obj, **kwargs)
docs: A rewrap of json.dumps done for one reason - to inject a custom `cls` kwarg
  
          :param obj:
          :param kwargs:
          :return:
          :rtype: str