Nix flakes explained

Enabling flakes:
nixos.wiki/wik... - commands are here
Creating a flake:
$ nix flake init
Updating a flake:
$ nix flake update
Flake:
```
{
description = "my epic vims collection";
inputs = {
nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
};
outputs = { self, nixpkgs }:
let
system = "x86_64-linux";
pkgs = nixpkgs.legacyPackages.${system};
in
{
bob =
pkgs.mkShell
{
buildInputs = [
pkgs.neovim
pkgs.vim
];
shellHook = ''
echo "hello mom"
'';
};
};
}
```
(yes, I know I could push it to github, but I'm extra lazy today)