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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_calls(data, cnv_only=False):
 """Retrieve calls, organized by name, to use for heterogeneity analysis. """

    cnvs_supported = set(["cnvkit", "battenberg"])
    out = {}
    for sv in data.get("sv", []):
        if not cnv_only or sv["variantcaller"] in cnvs_supported:
            out[sv["variantcaller"]] = sv
    return out