def list_all_files(self):
        """ Utility method that yields all files on the device's file
            systems.
        """
        def list_files_recursively(directory):
            f_gen = itertools.chain(
                directory.files,
                *tuple(list_files_recursively(d)
                       for d in directory.directories))
            for f in f_gen:
                yield f
        return list_files_recursively(self.filesystem)