Get a list of additional features

        Returns:
            Dict[str, Callable]: A dict of methods marked as additional features.
            Method can be called with ``get_extra_functions()["methodName"]()``.

def get_extra_functions(self) -> Dict[str, Callable]:
        """Get a list of additional features

        Returns:
            Dict[str, Callable]: A dict of methods marked as additional features.
            Method can be called with ``get_extra_functions()["methodName"]()``.
        """
        methods = {}
        for mName in dir(self):
            m = getattr(self, mName)
            if callable(m) and getattr(m, "extra_fn", False):
                methods[mName] = m
        return methods