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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 evaluate(data):
 """Provide evaluations for multiple callers split by structural variant type. """

    work_dir = utils.safe_makedir(os.path.join(data["dirs"]["work"], "structural",
                                               dd.get_sample_name(data), "validate"))
    truth_sets = tz.get_in(["config", "algorithm", "svvalidate"], data)
    if truth_sets and data.get("sv"):
        if isinstance(truth_sets, dict):
            val_summary, df_csv = _evaluate_multi(data["sv"], truth_sets, work_dir, data)
            summary_plots = _plot_evaluation(df_csv)
            data["sv-validate"] = {"csv": val_summary, "plot": summary_plots, "df": df_csv}
        else:
            assert isinstance(truth_sets, six.string_types) and utils.file_exists(truth_sets), truth_sets
            val_summary = _evaluate_vcf(data["sv"], truth_sets, work_dir, data)
            title = "%s structural variants" % dd.get_sample_name(data)
            summary_plots = validateplot.classifyplot_from_valfile(val_summary, outtype="png", title=title)
            data["sv-validate"] = {"csv": val_summary, "plot": summary_plots[0] if len(summary_plots) > 0 else None}
    return data