add dev environment

flake.nix

@@ -0,0 +1,23 @@
+{
+  description = "Shell with python dev environment";
+
+  inputs = {
+    nixpkgs.url = "nixpkgs/nixos-25.05";
+    nixpkgs_unstable.url = "nixpkgs/nixos-unstable";
+  };
+
+  outputs =
+    { nixpkgs, nixpkgs_unstable, ... }:
+    let
+      system = "x86_64-linux";
+      pkgs = nixpkgs.legacyPackages.${system};
+      pkgs_ustbl = nixpkgs_unstable.legacyPackages.${system};
+    in
+    {
+      devShells.${system}.default = nixpkgs.legacyPackages.${system}.mkShell {
+        buildInputs = [
+          pkgs.python311
+        ];
+      };
+    };
+}