Flying-Tiantian

Same problem with `nbconvert==7.2.1` and `mistune 2.0.4` When `pip list` shows nbconvert version number is 7.2.1, the _version.py file in installed pkg is: ``` version_info = (6, 4, 4) pre_info...

Reinstall nbconvert==7.2.1 with pip and `Found existing installation: nbconvert 6.4.4` 😥 Now everything works fine. But it is still weird because I setup the environment from a clean conda env.