安装了cocotb后，运行python,出现如下打印：

File "/home/virtualpc/.local/lib/python3.8/site-packages/cocotb/decorators.py", line 442, in __call__

return cocotb.scheduler._run_in_executor(self._func, *args, **kwargs)

AttributeError: 'NoneType' object has no attribute '_run_in_executor'

解决办法：

pip uninstall cocotb

19:02:52 ~/$ pip uninstall cocotb

Found existing installation: cocotb 1.7.2

Uninstalling cocotb-1.7.2:

Would remove:

/home/virtualpc/.local/bin/cocotb-config

/home/virtualpc/.local/lib/python3.8/site-packages/cocotb-1.7.2.dist-info/*

/home/virtualpc/.local/lib/python3.8/site-packages/cocotb/*

/home/virtualpc/.local/lib/python3.8/site-packages/pygpi/*

Proceed (Y/n)? y

Successfully uninstalled cocotb-1.7.2

不得已，只好删除了。