def METHOD_NAME():
    if sys.version_info[0] < 3:
        logging.critical ("Python 3 or a more recent version is required.")
    FEX_ROOTFS_MOUNT = os.getenv("FEX_ROOTFS_MOUNT")
    FEX_ROOTFS_PATH = os.getenv("FEX_ROOTFS_PATH")
    if FEX_ROOTFS_MOUNT == None:
        print("Need FEX_ROOTFS_MOUNT set")
        sys.exit(1)
    if FEX_ROOTFS_PATH == None:
        print("Need FEX_ROOTFS_PATH set")
        sys.exit(1)
    if shutil.which("unsquashfs") is None:
        print("CI system didn't have unsquashfs installed")
        sys.exit(1)
    Distro = GetDistroInfo()
    DistroFit = FindBestImageFit(Distro, FEX_ROOTFS_MOUNT + "/RootFS_links.txt")
    if CheckFilesystemForFS(FEX_ROOTFS_MOUNT, FEX_ROOTFS_PATH, DistroFit) == False:
        print("Couldn't load filesystem rootfs")
        sys.exit(1)
    return 0