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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 calculate_sv_bins(*items):
 """Determine bin sizes and regions to use for samples. Unified approach to prepare regional bins for coverage calculations across multiple CNV callers. Splits into target and antitarget regions allowing callers to take advantage of both. Provides consistent target/anti-target bin sizes across batches. Uses callable_regions as the access BED file and mosdepth regions in variant_regions to estimate depth for bin sizes. """

    calcfns = {"cnvkit": _calculate_sv_bins_cnvkit, "gatk-cnv": _calculate_sv_bins_gatk}
    from bcbio.structural import cnvkit
    items = [utils.to_single_data(x) for x in cwlutils.handle_combined_input(items)]
    if all(not cnvkit.use_general_sv_bins(x) for x in items):
        return [[d] for d in items]
    out = []
    for i, cnv_group in enumerate(_group_by_cnv_method(multi.group_by_batch(items, False))):
        size_calc_fn = MemoizedSizes(cnv_group.region_file, cnv_group.items).get_target_antitarget_bin_sizes
        for data in cnv_group.items:
            if cnvkit.use_general_sv_bins(data):
                target_bed, anti_bed, gcannotated_tsv = calcfns[cnvkit.bin_approach(data)](data, cnv_group,
                                                                                           size_calc_fn)
                if not data.get("regions"):
                    data["regions"] = {}
                data["regions"]["bins"] = {"target": target_bed, "antitarget": anti_bed, "group": str(i),
                                           "gcannotated": gcannotated_tsv}
            out.append([data])
    if not len(out) == len(items):
        raise AssertionError("Inconsistent samples in and out of SV bin calculation:\nout: %s\nin : %s" %
                             (sorted([dd.get_sample_name(utils.to_single_data(x)) for x in out]),
                              sorted([dd.get_sample_name(x) for x in items])))
    return out