Convert to JSON.

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

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

        Returns
        -------
        `dict`
            JSON data.
        """
        data = super().save()
        data['resize'] = list(self.resize) if self.resize is not None else None
        data['traversal'] = [t.save() for t in self.traversal]
        data['levels'] = self.levels
        data['level_scale'] = self.level_scale
        data['scale'] = self.scale
        return data