前言：用pip安裝wordcloud時提示：WARNING: You are using pip version 19.2.3, however version 20.2.3 is available.
于是開始升級pip（python -m pip install --upgrade pip），結(jié)果報錯 Consider using the `--user` option or check the permissions.

解決辦法：運行python -m ensurepip，后再運行python -m pip install --upgrade pip，之后便可安裝wordcloud了