Making a dev shell with nix flakes

from blog fasterthanli.me, | ↗ original
In the previous chapter, we've made a nix "dev shell" that contained the fly.io command-line utility, "flyctl". That said, that's not how I want us to define a dev shell. Our current solution has issues. I don't like that it has import . Which version of nixpkgs is that? The one you're on? Who knows what that is.