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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_variant_file(x, key, suffix="", sample=None, ignore_do_upload=False):
 """Retrieve VCF file with the given key if it exists, handling bgzipped. """

    out = []
    fname = utils.get_in(x, key)
    upload_key = list(key)
    upload_key[-1] = "do_upload"
    do_upload = tz.get_in(tuple(upload_key), x, True)
    if fname and (ignore_do_upload or do_upload):
        if fname.endswith(".vcf.gz"):
            out.append({"path": fname,
                        "type": "vcf.gz",
                        "ext": "%s%s" % (x["variantcaller"], suffix),
                        "variantcaller": x["variantcaller"]})
            if utils.file_exists(fname + ".tbi"):
                out.append({"path": fname + ".tbi",
                            "type": "vcf.gz.tbi",
                            "index": True,
                            "ext": "%s%s" % (x["variantcaller"], suffix),
                            "variantcaller": x["variantcaller"]})
        elif fname.endswith((".vcf", ".bed", ".bedpe", ".bedgraph", ".cnr", ".cns", ".cnn", ".txt", ".tsv")):
            ftype = utils.splitext_plus(fname)[-1][1:]
            if ftype == "txt":
                extended_ftype = fname.split("-")[-1]
                if "/" not in extended_ftype:
                    ftype = extended_ftype
            out.append({"path": fname,
                        "type": ftype,
                        "ext": "%s%s" % (x["variantcaller"], suffix),
                        "variantcaller": x["variantcaller"]})
    if sample:
        out_sample = []
        for x in out:
            x["sample"] = sample
            out_sample.append(x)
        return out_sample
    else:
        return out