anchor.diff:            }
           ];
   
  +      # !!! Use NixOS module system to add default attributes.
         addAttrs =
           { name
           , description
  
positive.code:         , createHome ? false
          , useDefaultShell ? false
          , password ? null
          }:
          { inherit name description uid group extraGroups home shell createHome password; };
  
      in map addAttrs (defaultUsers ++ config.users.extraUsers);
  
  
negative.code:             read shell
              read createHome
              read password
              read isSystemUser
  
              if ! curEnt=$(getent passwd "$name"); then
                  useradd ''${isSystemUser:+--system} \
                      --comment "$description" \
                      ''${uid:+--uid $uid} \
                      --gid "$group" \
  