def describe_security_groups(self, security_group_name):
        if security_group_name:
            if security_group_name in self.security_groups:
                return [self.security_groups[security_group_name]]
            else:
                raise DBSecurityGroupNotFoundError(security_group_name)
        return self.security_groups.values()
dataset/ETHPy150Open spulec/moto/moto/rds/models.py/RDSBackend.describe_security_groups/original