anchor.diff:    ###### interface
   
     options = {
  -  
       services.printing = {
   
         enable = mkOption {
  
positive.code:             mkdir -m 0755 -p ${logDir}
              mkdir -m 0700 -p /var/cache/cups
              mkdir -m 0700 -p /var/spool/cups
  
              # Make USB printers show up.
              ${modprobe}/sbin/modprobe usblp || true
  
negative.code:   # cupsd.conf tells cupsd to use this tree.
    bindir = pkgs.buildEnv {
      name = "cups-progs";
      paths = cfg.drivers;
      pathsToLink = [ "/lib/cups" "/share/cups" ];
      postBuild = cfg.bindirCmds;
    };
  
  in
  