'(typ, [data, ...]) = lsub(directory=\'""\', pattern=\'*\')
List \'subscribed\' mailbox names in directory matching pattern.
\'data\' are tuples of message part envelope and data.'

def lsub(self, directory='""', pattern='*', **kw):

    name = 'LSUB'
    kw['untagged_response'] = name
    return self._simple_command(name, directory, pattern, **kw)
