anchor.diff:  { package ? null
   , maintainer ? null
  +, path ? null
   }:
   
   # TODO: add assert statements
  
positive.code: 
          % nix-shell maintainers/scripts/update.nix --argstr package garbas
  
      to run update script for specific package.
    '';
  
    runUpdateScript = package: ''
  
negative.code:                    (name: pkg: pkg)
                     pkgs;
  
    packagesWithUpdateScript = path:
      let
        attrSet = pkgs.lib.attrByPath (pkgs.lib.splitString "." path) null pkgs;
      in
        packagesWith (name: pkg: builtins.hasAttr "updateScript" pkg)
                       (name: pkg: pkg)
                       attrSet;
  
    packageByName = name:
      let
          package = pkgs.lib.attrByPath (pkgs.lib.splitString "." name) null pkgs;
  