ERROR: Could not find a version that satisfies the requirement yaml (from versions: none)解决办法

报错：ERROR: Could not find a version that satisfies the requirement yaml (from versions: none)
ERROR: No matching distribution found for yaml

I thought it was because there was no yaml package in the source

Later, I found out that the original yaml package was called pyyaml, and installed it with the following command

pip install pyyaml

The installation is successful and the problem is solved