Convert to JSON.

        Returns
        -------
        `dict`
            JSON data.

def save(self):
        """Convert to JSON.

        Returns
        -------
        `dict`
            JSON data.
        """
        data = super().save()
        data['levels'] = self.levels
        if self.parsers is None:
            data['parsers'] = None
        else:
            data['parsers'] = [parser.save() for parser in self.parsers]
        return data