anchor.diff:            license = lib.licenses.free;
           };
         }) {};
  +    proof-general = callPackage ({ elpaBuild, emacs, fetchurl, lib }:
  +      elpaBuild {
  +        pname = "proof-general";
  +        ename = "proof-general";
  +        version = "4.5";
  +        src = fetchurl {
  +          url = "https://elpa.nongnu.org/nongnu/proof-general-4.5.tar";
  +          sha256 = "13zy339yz6ijgkcnqxzcyg909z77w3capb3gim1riy3sqikvv04x";
  +        };
  +        packageRequires = [ emacs ];
  +        meta = {
  +          homepage = "https://elpa.gnu.org/packages/proof-general.html";
  +          license = lib.licenses.free;
  +        };
  +      }) {};
       prop-menu = callPackage ({ cl-lib ? null, elpaBuild, emacs, fetchurl, lib }:
         elpaBuild {
           pname = "prop-menu";
  
positive.code:       elpaBuild {
          pname = "xah-fly-keys";
          ename = "xah-fly-keys";
          version = "17.13.20220526011611";
          src = fetchurl {
            url = "https://elpa.nongnu.org/nongnu/xah-fly-keys-17.13.20220526011611.tar";
            sha256 = "1lg8805s5y61jr6yrm44zdjm0nad6adc5xr78zm0i0qzigbhhdcq";
          };
          packageRequires = [ emacs ];
          meta = {
  
negative.code:       elpaBuild {
          pname = "apropospriate-theme";
          ename = "apropospriate-theme";
          version = "0.2.0";
          src = fetchurl {
            url = "https://elpa.nongnu.org/nongnu/apropospriate-theme-0.2.0.tar";
            sha256 = "1s4cvh24zj3wpdqc3lklvi1dkba3jf87nxrzq0s3l1rzhg21pfpj";
          };
          packageRequires = [];
          meta = {
  