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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 _run_paired(paired):
 """Run somatic variant calling pipeline. """

    from bcbio.structural import titancna
    work_dir = _sv_workdir(paired.tumor_data)
    seg_files = model_segments(tz.get_in(["depth", "bins", "normalized"], paired.tumor_data),
                               work_dir, paired)
    call_file = call_copy_numbers(seg_files["seg"], work_dir, paired.tumor_data)
    out = []
    if paired.normal_data:
        out.append(paired.normal_data)
    if "sv" not in paired.tumor_data:
        paired.tumor_data["sv"] = []
    paired.tumor_data["sv"].append({"variantcaller": "gatk-cnv",
                                    "call_file": call_file,
                                    "vrn_file": titancna.to_vcf(call_file, "GATK4-CNV", _get_seg_header,
                                                                _seg_to_vcf, paired.tumor_data),
                                    "seg": seg_files["seg"],
                                    "plot": plot_model_segments(seg_files, work_dir, paired.tumor_data)})
    out.append(paired.tumor_data)
    return out