class UnrecoverableException(object):
    pass


class BaseBackend(object):
    def __init__(self, app):
        self.app = app

    def create_build(self, build, project=None, project_entity=None):
        raise NotImplementedError

@@ -22,22 +22,25 @@
 ception(
-object
+Exception
 ):%0A    p

Correct exception class