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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 _finalize_merge(out_file, bam_files, config):
 """Handle indexes and cleanups of merged BAM and input files. """

    # Ensure timestamps are up to date on output file and index
    # Works around issues on systems with inconsistent times
    for ext in ["", ".bai"]:
        if os.path.exists(out_file + ext):
            subprocess.check_call(["touch", out_file + ext])
    for b in bam_files:
        utils.save_diskspace(b, "BAM merged to %s" % out_file, config)