为了使用jupyter，安装nb_conda遇到如下问题，起初判断为conda版本问题，update后依然报错
UnsatisfiableError: The following specifications were found
to be incompatible with the existing python installation in your environment:
Specifications:
- nb_conda -> python[version='>=2.7,<2.8.0a0|>=3.5,<3.6.0a0|>=3.8,<3.9.0a0|>=3.6,<3.7.0a0|>=3.7,<3.8.0a0']
Your python: python=3.9
If python is on the left-most side of the chain, that's the version you've asked for.
When python appears to the right, that indicates that the thing on the left is somehow
not available for the python version you are constrained to. Note that conda will not
change your python version to a different minor version unless you explicitly specify
that.大致意思就是我的python -version为3.9，与nb_conda -version不兼容，
这样的话我们利用anaconda创建一个3.8version的环境，
注：两种环境不发生冲突
下面是解决过程：
打开anaconda prompt
?输入以下命令，创建3.8版本环境
conda create -n python38 python=3.8
安装完毕后? 可输入查看当前环境
conda env list
?这时可以再anaconda中看到新建的python3.8，点击python38，重新安装nb_conda，显示成功。
注：不同环境不会共享库，意味着新的3.8环境需要重新下载numpy库等
?