reformat all the nix files

using
    nix run -f channel:nixos-unstable nixfmt -c nixfmt $(git ls-files *.nix)

role/backup/default.nix

@@ -1,33 +1,29 @@
 # Regular backup role to a separate device
-{
- systemdMount, # Systemd mount name
- borgArchiveFolder, # Absolute borg root folder
- keepWithin? "14d",
- keepWeekly? "4",
- keepMonthly? "6",
- keepYearly? "-1",
- schedule? "13:37", # Systemd Schedule of backup timer
+{ systemdMount, # Systemd mount name
+borgArchiveFolder, # Absolute borg root folder
+keepWithin ? "14d", keepWeekly ? "4", keepMonthly ? "6", keepYearly ? "-1"
+, schedule ? "13:37", # Systemd Schedule of backup timer
 }:
 
-let pkgs = import<nixpkgs>{};
-in
-{
+let pkgs = import <nixpkgs> { };
+in {
 
-  systemd =  {
+  systemd = {
     services.backup = {
-      description = "Backup of all user data and system configuration with BorgBackup";
+      description =
+        "Backup of all user data and system configuration with BorgBackup";
       serviceConfig.Type = "oneshot";
       path = with pkgs; [ bash borgbackup ];
       script = ''
         #!/usr/bin/env bash
         set -euo pipefail
         IFS=$'\n\t'
-        
+
         systemctl start ${systemdMount}
 
         export BORG_REPO=${borgArchiveFolder} \
                BORG_BASE_DIR=${borgArchiveFolder}/borg-base-dir
-        
+
         echo "Backup started at `date`"
         borg create --exclude /var/backup \
                     --exclude /var/tmp \
@@ -37,10 +33,10 @@ in
                     /home \
                     /root \
                     /var
-        
+
         sync
         echo "Backup finished at `date`"
-        
+
         echo "Backup prune started at `date`"
         borg prune --prefix '{hostname}-' \
                    --keep-within  ${keepWithin} \