'Validate the options, returning True if they are indeed valid.
It would be nice to use the argparse automated checking for this
validation, but the only way I can see doing that is to make the
default (i.e. if no optional parameters are specified) to upload
all configuration files - and that sounds too dangerous as a
default. So we use it in a slightly unconventional way, where all
parameters are optional, but you must specify at least one.'

def valid_options(self):

    if ((CONF.command.all is False) and (CONF.command.domain_name is None)):
        print(_('At    least    one    option    must    be    provided,    use    either    --all    or    --domain-name'))
        return False
    if ((CONF.command.all is True) and (CONF.command.domain_name is not None)):
        print(_('The    --all    option    cannot    be    used    with    the    --domain-name    option'))
        return False
    return True
