def _init_flow_exceptions():
 global _flow_exceptions
 _flow_exceptions = ()
 add_flow_exception(datastore_errors.Rollback)
 try:
  from webob import exc
 except ImportError:
  pass
 else:
  add_flow_exception(exc.HTTPException)

def _init_flow_exceptions ( ) : global _flow_exceptions _flow_exceptions = ( ) add_flow_exception ( datastore_errors . Rollback ) try : from webob import exc except ImportError : pass else : add_flow_exception ( exc . HTTPException )
internal helper to initialize _flow_exceptions .