Prospective Search Exceptions (Python)

The google.appengine.api.prospective_search package provides the following exception classes derived from the base prospective_search.Error:

exception QuerySyntaxError()
Query syntax is invalid or refers to a field that does not exist in the document schema. See Query Language Overview.
exception apiproxy_errors.Error
The function call failed. This may occur if there is an internal error. This exception is unlikely to be due to a problem with the application.
exception SubscriptionDoesNotExist()
Subscription does not exist. Use list_subscriptions() to see all currently registered subscriptions.