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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 _save_fastq_space(items):
 """Potentially save fastq space prior to merging, since alignments done. """

    to_cleanup = {}
    for data in (utils.to_single_data(x) for x in items):
        for fname in data.get("files", []):
            if os.path.realpath(fname).startswith(dd.get_work_dir(data)):
                to_cleanup[fname] = data["config"]
    for fname, config in to_cleanup.items():
        utils.save_diskspace(fname, "Cleanup prep files after alignment finished", config)