+ xo-pyjit + ::endgroup in github workflow

pkgs/xo-pyjit.nix

@@ -0,0 +1,39 @@
+{
+  # nixpkgs dependencies
+  stdenv, cmake, catch2, # ... other deps here
+
+  # xo dependencies
+  xo-cmake, xo-pyutil, xo-jit,
+
+  xo-pyexpression,
+  #xo-pyreflect,
+
+  # args
+
+  #   attrset for fetching source code.
+  #    { type, owner, repo, ref }
+  #
+  #   e.g. type="github", owner="rconybea", repo="cmake-examples", ref="ex1b"
+  #
+  #   see [[../flake.nix]]
+  #
+  #cmake-examples-ex1-path
+
+  # someconfigurationoption ? false
+} :
+
+stdenv.mkDerivation (finalattrs:
+  {
+    name = "xo-pyjit";
+    version = "1.0";
+
+    src = ../xo-pyjit;
+
+    cmakeFlags = ["-DCMAKE_MODULE_PATH=${xo-cmake}/share/cmake"];
+    doCheck = true;
+    nativeBuildInputs = [ cmake catch2 xo-cmake ];
+    propagatedBuildInputs = [ xo-pyutil
+                              #xo-pyreflect
+                              xo-pyexpression
+                              xo-jit ];
+  })

pkgs/xo-userenv.nix

@@ -53,7 +53,7 @@
   xo-tokenizer,
   xo-reader,
   xo-jit,
-#  xo-pyjit
+  xo-pyjit
 
   # other args