code: def list_by_instance(self, instance_id):
          
          ports = port_list(self.request, device_id=instance_id)
          sg_ids = []
          for p in ports:
              sg_ids += p.security_groups
          return self._list(id=set(sg_ids)) if sg_ids else []
docs: Gets security groups of an instance.
  
          :returns: List of SecurityGroup objects associated with the instance