Add section on using other flakes in your own

readme.md

@@ -230,28 +230,46 @@ can make use of it. Try it out now!
 
 > Note: The following obviously runs code from the internet. Be wary of doing this in general.
 
+Run a flake's package:
+
 ```console
-# run a flake's package
 $ nix run git+https://git.lyte.dev/lytedev/learn-flakes-the-fun-way
 24.5.113.148
+```
 
-# enter a flake's development environment
+Enter a flake's development environment:
+
+```console
 $ nix develop git+https://git.lyte.dev/lytedev/learn-flakes-the-fun-way -c $SHELL
 Hello, Nix!
 $ what-is-my-ip
 24.5.113.148
 
-# load a flake's docker image and run it
+# want to hack on the Helix text editor?
+$ nix develop github:helix-editor/helix
+# yeah, seriously! that's it!
+```
+
+Load a flake's docker image and run it:
+
+```console
 $ docker load < $(nix build git+https://git.lyte.dev/lytedev/learn-flakes-the-fun-way#container --print-out-paths)
 Loaded image: what-is-my-ip-container:wg0z43v4sc1qhq7rsqg02w80vsfk9dl0
 $ docker run -it what-is-my-ip-container:c9g6x30invdq1bjfah3w1aw5w52vkdfn
+```
 
-# run a flake's NixOS configuration as a virtual machine
+Run a flake's NixOS configuration as a virtual machine:
+
+```console
 $ nixos-rebuild build-vm --flake git+https://git.lyte.dev/lytedev/learn-flakes-the-fun-way#default
 Done.  The virtual machine can be started by running /nix/store/xswwdly9m5bwhcz9ajd6km5hx9vdmfzw-nixos-vm/bin/run-nixos-vm
 $ /nix/store/xswwdly9m5bwhcz9ajd6km5hx9vdmfzw-nixos-vm/bin/run-nixos-vm
+```
 
-# like running a pre-configured version of my workstation's NixOS configuration
+Run an exact replica my workstation in a virtual machine (as configured via Nix
+-- meaning it will not have my passwords on it 😉):
+
+```console
 # NOTE: this will probably take a good, long time to build and lots of bandwidth
 # NOTE: you probably won't even be able to login
 $ nixos-rebuild build-vm --flake git+https://git.lyte.dev/lytedev/nix#dragon
@@ -259,6 +277,68 @@ Done.  The virtual machine can be started by running /nix/store/abc-nixos-vm/bin
 $ /nix/store/abc-nixos-vm/bin/run-dragon-vm
 ```
 
+Finally, Flakes can take any other Flake as input and use them for their own outputs. This means that they compose wonderfully. Any Flake can use anything from any other Flake. They're basically big ol' distributed functions (if you squint just right).
+
+You can generate your own flake however you like; Flakes provide templating
+facilities. Here, you can use my very own template:
+
+```console
+$ mkdir -p ~/my-fun-flake
+$ cd ~/my-fun-flake
+$ nix flake init --template git+https://git.lyte.dev/lytedev/nix#nix-flake
+$ git init
+$ git add -A
+$ git commit -am 'initial commit'
+$ nix develop -c $SHELL
+```
+
+And now you have everything you need to work on a Nix flake as if you were me!
+
+To add the package from this tutorial, we can simply do this:
+
+```diff
+diff --git a/flake.nix b/flake.nix
+index 408d4f2..c5d6883 100644
+--- a/flake.nix
++++ b/flake.nix
+@@ -2,16 +2,20 @@
+   inputs.pre-commit-hooks.url = "github:cachix/pre-commit-hooks.nix";
+   inputs.pre-commit-hooks.inputs.nixpkgs.follows = "nixpkgs";
+ 
++  inputs.learn-flakes-the-fun-way.url = "git+https://git.lyte.dev/lytedev/learn-flakes-the-fun-way";
++  inputs.learn-flakes-the-fun-way.inputs.nixpkgs.follows = "nixpkgs";
++
+   outputs = {
+     self,
+     nixpkgs,
+     pre-commit-hooks,
++    learn-flakes-the-fun-way,
+     ...
+   }: let
+     systems = ["aarch64-linux" "aarch64-darwin" "x86_64-darwin" "x86_64-linux"];
+     forSystems = nixpkgs.lib.genAttrs systems;
+   in {
+     formatter = genPkgs (pkgs: pkgs.alejandra);
+ 
+@@ -26,7 +30,7 @@
+ 
+     devShells = genPkgs (pkgs: {
+       nix = pkgs.mkShell {
+-        packages = with pkgs; [nil alejandra];
++        packages = with pkgs; [nil alejandra learn-flakes-the-fun-way.packages.${pkgs.system}.default];
+         inherit (self.outputs.checks.${pkgs.system}.pre-commit-check) shellHook;
+       };
+
+```
+
+Afterwards you can re-enter your development shell and run our script:
+
+```console
+$ nix develop -c $SHELL
+$ what-is-my-ip
+24.5.113.148
+```
+
 Hopefully, seeing the _fun things_ you can do with Nix might inspire you to push through the hard parts.
 
 There is a golden pot 💰 at the end of this rainbow 🌈 awaiting you.