anchor.diff:          let &rtp.=(empty(&rtp)?"":',')."${vimPlugins.pathogen.rtp}"
           execute pathogen#infect('${pluginsEnv}/{}')
         '');
  +
  +      /* vim-plug is an extremely popular vim plugin manager.
  +      */
  +      plugImpl = lib.optionalString (plug != null)
  +      ''
  +        source ${vimPlugins.vim-plug.rtp}/plug.vim
  +        call plug#begin('/dev/null')
  +
  +        '' + (lib.concatMapStringsSep "\n" (pkg: "Plug '${pkg.rtp}'") plug.plugins) + ''
  +
  +        call plug#end()
  +      '';
   
         /*
          vim-addon-manager = VAM
  
positive.code:     packages ? null,
      vam ? null,
      pathogen ? null,
      customRC ? ""
    }:
  
  
negative.code: 
    ${vamImpl}
    ${pathogenImpl}
    ${plugImpl}
    ${vundleImpl}
    ${neobundleImpl}
    ${nativeImpl}
  