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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_evidence_bam(work_dir, data):
 """Retrieve evidence BAM for the sample if it exists """

    evidence_bam = glob.glob(os.path.join(work_dir, "results", "evidence",
                                            "evidence_*.%s*.bam" % (dd.get_sample_name(data))))
    if evidence_bam:
        return evidence_bam[0]