Retrieve set of variant calls to use for heterogeneity analysis.

def get_variants(data, include_germline=False):
    """Retrieve set of variant calls to use for heterogeneity analysis.
    """
    data = utils.deepish_copy(data)
    supported = ["precalled", "vardict", "vardict-java", "vardict-perl",
                 "freebayes", "octopus", "strelka2"]
    # Right now mutect2 and mutect do not provide heterozygous germline calls
    # to be useful https://github.com/bcbio/bcbio-nextgen/issues/2464
    # supported += ["mutect2", "mutect"]
    if include_germline:
        supported.insert(1, "gatk-haplotype")
    out = []
    # CWL based input
    if isinstance(data.get("variants"), dict) and "samples" in data["variants"]:
        cur_vs = []
        # Unpack single sample list of files
        if (isinstance(data["variants"]["samples"], (list, tuple)) and
              len(data["variants"]["samples"]) == 1 and isinstance(data["variants"]["samples"][0], (list, tuple))):
            data["variants"]["samples"] = data["variants"]["samples"][0]
        for fname in data["variants"]["samples"]:
            variantcaller = utils.splitext_plus(os.path.basename(fname))[0]
            variantcaller = variantcaller.replace(dd.get_sample_name(data) + "-", "")
            for batch in dd.get_batches(data):
                variantcaller = variantcaller.replace(batch + "-", "")
            cur_vs.append({"vrn_file": fname, "variantcaller": variantcaller})
        data["variants"] = cur_vs
    for v in data.get("variants", []):
        if v["variantcaller"] in supported and v.get("vrn_file"):
            out.append((supported.index(v["variantcaller"]), v))
    out.sort()
    return [xs[1] for xs in out]