问Python3.9导入方面的cryptography.fernet错误

EN

from cryptography.fernet import Fernet

Traceback (most recent call last):
File "C:\Program Files\Python39\lib\runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
File "C:\Program Files\Python39\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
File "c:\Users\USERNAME\.vscode\extensions\ms-python.python-2022.8.1\pythonFiles\lib\python\debugpy\__main__.py", line 45, in <module>
    cli.main()
File "c:\Users\USERNAME\.vscode\extensions\ms-python.python-2022.8.1\pythonFiles\lib\python\debugpy/..\debugpy\server\cli.py", line 444, in main
    run()
File "c:\Users\USERNAME\.vscode\extensions\ms-python.python-2022.8.1\pythonFiles\lib\python\debugpy/..\debugpy\server\cli.py", line 285, in run_file
    runpy.run_path(target_as_str, run_name=compat.force_str("__main__"))
File "C:\Program Files\Python39\lib\runpy.py", line 267, in run_path
    code, fname = _get_code_from_file(run_name, path_name)
File "C:\Program Files\Python39\lib\runpy.py", line 242, in _get_code_from_file
    code = compile(f.read(), fname, 'exec')
ValueError: source code string cannot contain null bytes