def METHOD_NAME():
    backend_name = None
    # User-selected backend
    config_path = os.path.join(os.path.expanduser("~"), ".deepxde", "config.json")
    if "DDE_BACKEND" in os.environ:
        backend_name = os.getenv("DDE_BACKEND")
    # Backward compatibility
    elif "DDEBACKEND" in os.environ:
        backend_name = os.getenv("DDEBACKEND")
    elif os.path.exists(config_path):
        with open(config_path, "r") as config_file:
            config_dict = json.load(config_file)
            backend_name = config_dict.get("backend", "").lower()
    if backend_name is not None:
        verify_backend(backend_name)
        return backend_name
    # No backend selected
    print("No backend selected.")
    # Find available backend
    print("Finding available backend...")
    backend_name = get_available_backend()
    if backend_name is not None:
        print(f"Found {backend_name}")
        set_default_backend(backend_name)
        return backend_name
    # No backend available
    print("Cannot find available backend.")
    interactive_install_paddle()
    set_default_backend("paddle")
    return "paddle"