anchor.diff:        utillinux # needed for mount and mountpoint
       ];
   
  +  scriptType = with types;
  +    let scriptOptions =
  +      { deps = mkOption
  +          { type = types.listOf types.str;
  +            default = [ ];
  +            description = "List of dependencies. The script will run after these.";
  +          };
  +        text = mkOption
  +          { type = types.lines;
  +            description = "The content of the script.";
  +          };
  +      };
  +    in either str (submodule { options = scriptOptions; });
  +
   in
   
   {
  
positive.code:         idempotent and fast.
        '';
  
        type = types.attrsOf types.unspecified;
  
        apply = set: {
          script = ''
  
negative.code:       default = {};
  
        example = literalExample ''
          { stdio.text =
            '''
              # Needed by some programs.
              ln -sfn /proc/self/fd /dev/fd
              ln -sfn /proc/self/fd/0 /dev/stdin
              ln -sfn /proc/self/fd/1 /dev/stdout
              ln -sfn /proc/self/fd/2 /dev/stderr
            ''';
          }
        '';
  
  