anchor.diff:              example = true;
               type = types.bool;
               description = "
  -              Cipher the swap device to protect swapped data.
  +              Cipher the swap device to protect swapped data.  This option
  +              does not work with labels.
               ";
             };
   
  
positive.code: 
      jobs.swap =
        { task = true;
          
          startOn = ["startup" "new-devices"];
  
          script =
            ''
              ${toString (map (x: x.command) config.swapDevices)}
  
              # Remove swap devices not listed in swapDevices.
              for used in $(cat /proc/swaps | grep '^/' | sed 's/ .*//'); do
                  found=
                  for device in $swapDevices; do
                      device=$(readlink -f $device)
                      if test "$used" = "$device"; then found=1; fi
                  done
                  if test -z "$found"; then
                      ${utillinux}/sbin/swapoff "$used" || true
                  fi
              done
            '';
        };
  
  
negative.code:     };
  
    };
  
    ###### implementation
  
  