'Check that all required settings were specified in the config.
Raises ConfigError otherwise.
Note that if a setting specified has required=True and
default is not None then this method will not raise an error
because a default was given. In short, if a setting is required
you must provide None as the \'default\' value.'

def _check_required(self, section_name, settings, store):

    section_conf = store
    for setting in settings:
        requirements = settings[setting]
        required = requirements[1]
        value = section_conf.get(setting)
        if ((value is None) and required):
            raise exception.ConfigError(('missing    required    option    %s    in    section    "%s"' % (setting, section_name)))
