def show_matching_files(matching_files: list, tag: str) ->None:
    """Print the list of matching files. Or a notification if there were no results."""
    if matching_files is None:
        msg = 'No matching files with "{}" tag.\n\nMisspelled? or inexistent?'
        msg = msg.format(tag)
        print(msg)
        return
    msg = '{} matching files under tag "{}":'
    print(msg.format(len(matching_files), tag))
    for f in matching_files:
        print('\t{}'.format(f))
