def _to_dict(self):
        """Return a json dictionary representing this model."""
        _dict = {}
        if hasattr(self, 'duration') and self.duration is not None:
            _dict['duration'] = self.duration
        if hasattr(self, 'name') and self.name is not None:
            _dict['name'] = self.name
        if hasattr(self, 'details') and self.details is not None:
            _dict['details'] = self.details._to_dict()
        if hasattr(self, 'status') and self.status is not None:
            _dict['status'] = self.status
        return _dict