<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def cache(ctx, clear_subliminal):
 """Cache management."""

    if clear_subliminal:
        for file in glob.glob(os.path.join(ctx.parent.params['cache_dir'], cache_file) + '*'):
            os.remove(file)
        click.echo('Subliminal\'s cache cleared.')
    else:
        click.echo('Nothing done.')