anchor.diff:            -L "$melpa/package-build" \
             -l "$melpa2nix" \
             -f melpa2nix-build-package \
  -          $pname $version
  +          $ename $version
   
         runHook postBuild
       '';
  
positive.code: 
  with lib;
  
  { pname
  , version
  , recipe
  , meta ? {}
  
negative.code: 
    postUnpack = ''
      mkdir -p "$NIX_BUILD_TOP/working"
      ln -s "$NIX_BUILD_TOP/$sourceRoot" "$NIX_BUILD_TOP/working/$ename"
    '';
  
    buildPhase =
  