code: def apply_status_code(self, status_code):
          
          self._check_ended()
          if not status_code:
              return
  
          if status_code >= 500:
              self.add_fault_flag()
          elif status_code == 429:
              self.add_throttle_flag()
              self.add_error_flag()
          elif status_code >= 400:
              self.add_error_flag()
docs: When a trace entity is generated under the http context,
          the status code will affect this entity's fault/error/throttle flags.
          Flip these flags based on status code.