'Get the list of quota roots for the named mailbox.
(typ, [[QUOTAROOT responses...], [QUOTA responses]]) = <instance>.getquotaroot(mailbox)'

def getquotaroot(self, mailbox):

    (typ, dat) = self._simple_command('GETQUOTAROOT', mailbox)
    (typ, quota) = self._untagged_response(typ, dat, 'QUOTA')
    (typ, quotaroot) = self._untagged_response(typ, dat, 'QUOTAROOT')
    return (typ, [quotaroot, quota])
