'(typ, [data]) = <instance>.getannotation(mailbox, entry, attribute)
Retrieve ANNOTATIONs.'

def getannotation(self, mailbox, entry, attribute):

    (typ, dat) = self._simple_command('GETANNOTATION', mailbox, entry, attribute)
    return self._untagged_response(typ, dat, 'ANNOTATION')
