def METHOD_NAME():
    args = parse_args()
    disa_xccdftree = ET.parse(args.disa_xccdf_filename)
    if not args.ssg_xccdf_filename:
        prompt = True
        if not args.quiet:
            print("WARNING: You are generating a STIG overlay XML file without mapping it "
                "to existing SSG content.")
            prompt = yes_no_prompt()
        if not prompt:
            sys.exit(0)
        ssg_xccdftree = False
    else:
        ssg_xccdftree = ET.parse(args.ssg_xccdf_filename)
        ssg = ssg_xccdftree.find(".//{%s}publisher" % dc_ns).text
        if ssg != "SCAP Security Guide Project":
            if not args.quiet:
                sys.exit("%s is not a valid SSG generated XCCDF file." % args.ssg_xccdf_filename)
            else:
                sys.exit(1)
    disa = disa_xccdftree.find(".//{%s}source" % dc_ns).text
    if disa != "STIG.DOD.MIL":
        if not args.quiet:
            sys.exit("%s is not a valid DISA generated manual XCCDF file." % args.disa_xccdf_filename)
        else:
            sys.exit(2)
    new_stig_overlay(disa_xccdftree, ssg_xccdftree, args.output_file, args.quiet)