Returns:
            str | None: First available usable location

def usable_location(self):
        """
        Returns:
            str | None: First available usable location
        """
        if self.file_location is not None:
            # Custom location typically provided via --config CLI flag
            return self._auto_complete_filename(self.file_location)
        if self.locations:
            for location in self.locations:
                path = self._auto_complete_filename(location)
                if path:
                    return path