anchor.diff:    users = config.users;
   
     userOpts = { name, config, ... }: {
  -  
  +
       options = {
  -    
  +
         name = mkOption {
           type = with types; uniq string;
           description = "The name of the user account. If undefined, the name of the attribute set will be used.";
         };
  -      
  +
         description = mkOption {
           type = with types; uniq string;
           default = "";
           description = "A short description of the user account.";
         };
  -      
  +
         uid = mkOption {
           type = with types; uniq (nullOr int);
           default = null;
           description = "The account UID. If undefined, NixOS will select a free UID.";
         };
  -      
  +
         group = mkOption {
           type = with types; uniq string;
           default = "nogroup";
           description = "The user's primary group.";
         };
  -      
  +
         extraGroups = mkOption {
           type = types.listOf types.string;
           default = [];
           description = "The user's auxiliary groups.";
         };
  -      
  +
         home = mkOption {
           type = with types; uniq string;
           default = "/var/empty";
           description = "The user's home directory.";
         };
  -      
  +
         shell = mkOption {
           type = with types; uniq string;
           default = "/run/current-system/sw/sbin/nologin";
           description = "The path to the user's shell.";
         };
  -      
  +
         createHome = mkOption {
           type = types.bool;
           default = false;
           description = "If true, the home directory will be created automatically.";
         };
  -      
  +
         useDefaultShell = mkOption {
           type = types.bool;
           default = false;
           description = "If true, the user's shell will be set to <literal>users.defaultUserShell</literal>.";
         };
  -      
  +
         password = mkOption {
           type = with types; uniq (nullOr string);
           default = null;
           description = "The user's password. If undefined, no password is set for the user.  Warning: do not set confidential information here because this data would be readable by all.  This option should only be used for public account such as guest.";
         };
  -      
  +
         isSystemUser = mkOption {
           type = types.bool;
           default = true;
           description = "Indicates if the user is a system user or not.";
         };
  -      
  +
         createUser = mkOption {
           type = types.bool;
           default = true;
  
positive.code:           then not modify any of the basic properties for the user account.
          ";
        };
        
      };
  
      config = {
  
negative.code:             read password
              read isSystemUser
              read createUser
              read isAlias
  
              if [ -z "$createUser" ]; then
                  continue
              fi
  
  