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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def cleanup():
 """Cleanup the output directory"""

    if _output_dir and os.path.exists(_output_dir):
        log.msg_warn("Cleaning up output directory at '{output_dir}' ..."
                     .format(output_dir=_output_dir))
        if not _dry_run:
            shutil.rmtree(_output_dir)