运行main时候报错

运行main时候提示：

Traceback (most recent call last):

  File "D:\anaconda3\envs\cv\lib\inspect.py", line 1285, in getfullargspec

    sig = _signature_from_callable(func,

  File "D:\anaconda3\envs\cv\lib\inspect.py", line 2390, in _signature_from_callable

    raise TypeError('{!r} is not a callable object'.format(obj))

TypeError: None is not a callable object

The above exception was the direct cause of the following exception:

Traceback (most recent call last):

  File "D:\WorkSpace\learn_gradio\main.py", line 3, in <module>

    demo = gr.Interface(fn=None,inputs="text",outputs="text")

  File "D:\anaconda3\envs\cv\lib\site-packages\gradio\interface.py", line 376, in __init__

    param_names = inspect.getfullargspec(self.fn)[0]

  File "D:\anaconda3\envs\cv\lib\inspect.py", line 1295, in getfullargspec

    raise TypeError('unsupported callable') from ex

TypeError: unsupported callable

IMPORTANT: You are using gradio version 3.50.2, however version 4.44.1 is available, please upgrade.

这是什么原因呢

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