anchor.diff:            [
               buildPackages.bison
               buildPackages.flex
  -            buildPackages.lowdown
  +            (lib.getBin buildPackages.lowdown)
               buildPackages.mdbook
               buildPackages.autoconf-archive
               buildPackages.autoreconfHook
  
positive.code: 
            src = lowdown-src;
  
            outputs = [ "out" "dev" ];
  
            nativeBuildInputs = [ which ];
  
  
negative.code:             ''
                ./configure \
                  PREFIX=${placeholder "dev"} \
                  BINDIR=${placeholder "bin"}/bin
              '';
          };
  
  