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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 split_variants_by_sample(data):
 """Split a multi-sample call file into inputs for individual samples. For tumor/normal paired analyses, do not split the final file and attach it to the tumor input. """

    # not split, do nothing
    if "group_orig" not in data:
        return [[data]]
    # cancer tumor/normal
    elif (vcfutils.get_paired_phenotype(data)
            and "tumor" in [vcfutils.get_paired_phenotype(d) for d in get_orig_items(data)]):
        out = []
        for i, sub_data in enumerate(get_orig_items(data)):
            if vcfutils.get_paired_phenotype(sub_data) == "tumor":
                cur_batch = tz.get_in(["metadata", "batch"], data)
                if cur_batch:
                    sub_data["metadata"]["batch"] = cur_batch
                sub_data["vrn_file"] = data["vrn_file"]
            else:
                sub_data.pop("vrn_file", None)
            out.append([sub_data])
        return out
    # joint calling or population runs, do not split back up and keep in batches
    else:
        out = []
        for sub_data in get_orig_items(data):
            cur_batch = tz.get_in(["metadata", "batch"], data)
            if cur_batch:
                sub_data["metadata"]["batch"] = cur_batch
            sub_data["vrn_file_batch"] = data["vrn_file"]
            sub_data["vrn_file"] = data["vrn_file"]
            out.append([sub_data])
        return out