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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 get_cufflinks():
    "Download cufflinks GTF files"
    for size, md5, url in cufflinks:
        cuff_gtf = os.path.join(args.data_dir, os.path.basename(url))
        if not _up_to_date(md5, cuff_gtf):
            download(url, cuff_gtf)