Require python3-ruamel-yaml
    
    Or you'll get:
    
        >>> import _ruamel_yaml
        Traceback (most recent call last):
          File "<stdin>", line 1, in <module>
          File "ruamel.yaml.clib/_ruamel_yaml.pyx", line 17, in init _ruamel_yaml
        ModuleNotFoundError: No module named 'ruamel'