Add missing docstring section
@@ -269,6 +269,8 @@ class TransactionManager(object):
Args:
project_id: A string specifying a project ID.
xg: A boolean indicating a cross-group transaction.
+ Returns:
+ An integer specifying the created transaction ID.
Raises:
BadRequest if the project does not exist.
InternalError if unable to create a new transaction ID.
