> Pretty sure you can use == in requirements.txt You can, but one of those packages that you depend on will have a loose version spec for one of its dependenci

> Pretty sure you can use == in requirements.txt You can, but one of those packages that you depend on will have a loose version spec for one of its dependencies, making your `pip install -r requirements.txt` non-deterministic. Poetry and Pipenv solve this, though, by pinning all dependencies in a lock file.