code: def restore_backup(self, backup, name, flavor, volume):
          
          flavor_ref = self.api._get_flavor_ref(flavor)
          body = {"instance": {
                  "name": name,
                  "flavorRef": flavor_ref,
                  "volume": {"size": volume},
                  "restorePoint": {"backupRef": utils.get_id(backup)},
                  }}
          uri = "/%s" % self.uri_base
          resp, resp_body = self.api.method_post(uri, body=body)
          return CloudDatabaseInstance(self, resp_body.get("instance", {}))
docs: Restores a backup to a new database instance. You must supply a backup
          (either the ID or a CloudDatabaseBackup object), a name for the new
          instance, as well as a flavor and volume size (in GB) for the instance.