code: def service_unavailable(cls, errors=None):
          
          if cls.expose_status:  # pragma: no cover
              cls.response.content_type = 'application/json'
              cls.response._status_line = '503 Service Unavailable'
  
          return cls(503, None, errors).to_json
docs: Shortcut API for HTTP 503 `Service Unavailable` response.
  
          Args:
              errors (list): Response key/value data.
  
          Returns:
              WSResponse Instance.