imp: add combinator

```nix
{
  foo = combine (update [0] ["bar"]) (append ["qux"]);
}

```

Author: blaggacao

Diff for: flake.nix

@@ -187,6 +187,12 @@
       append = new: orig: here: orig ++ (list any new);
       # ------
 
+      # ------
+      # combine
+      # ------
+      combine = first: second: orig: here: (function second) ((function first) orig here) orig here;
+      # ------
+
       # ------
       # update
       # ------