That's a great a vote of confidence. I would've thought that nix would only manage packages on the OS-level. How does it re-implement pip to be reliable? I c

That's a great a vote of confidence. I would've thought that nix would only manage packages on the OS-level. How does it re-implement pip to be reliable? I currently have to stage a couple of `apt-gets` and `pip installs` before my `pip install requirements`, and it took a couple of tries to lock in the right sequence that worked. How does nix solve those problems?