example.py

class Bundle(dict)
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._normalize_bundle()

    def _normalize_bundle(self):
        """ Normalizes bundle for things
        like applications vs. services
        """
        if 'services' in self:
            self['applications'] = self.pop('services')

    def to_yaml(self):
        """ Returns yaml dump of bundle
        """
        return yaml.dump(self,
                         default_flow_style=False)

    @property
    def applications(self):
        """ Returns list of applications/services
        """
        _applications = []
        for app in self['applications'].keys():
            _applications.append(self._get_application_fragment(app))
        return _applications

    @property
    def machines(self):
        """ Returns defined machines
        """
        return self.get('machines', [])