def list_representatives(GCF_dict):
    """retrieves the represenatives
    ----------
    GCF_dict
        dictionary, {Representative: family members}
    returns
    ----------
    outlist: list, list of filenames
    """
    outlist = []

   # with open(json_file, "r") as jfile:
   #     GCF_dict = json.load(jfile)

    for key in GCF_dict.keys():
        GC_or_HG = key.split("|")[2].split("_")[0]
        if GC_or_HG == "GC":
            orgID = key.split("|")[1]
            filename = f"{orgID}.gbk"
            outlist.append(filename)
        else:
            pass
    return (outlist)