Looking in indexes: https://pypi.tuna.tsinghua.edu.cn/simple

This message usually appears when you are trying to install a Python package using pip and it is searching for the package in the indexes specified in your pip configuration. In this case, it is searching for the package in the Tsinghua University mirror.

If you have configured pip to use this mirror, it will try to download the package from there. If the package is found, it will be installed. Otherwise, pip will look for the package in other indexes specified in your configuration.

If you don't want to use the Tsinghua mirror, you can remove it from your configuration or specify a different mirror to use. To do this, you can edit your pip configuration file or use the `--index-url` option with pip.