code: function notfoundUnit (server) {
    var regexes = [];
    var callbacks = [];
  
    function notfound (paths, literalCall) {
      regexes.push(RegExp(paths));
      callbacks.push(literalCall);
    }
  
    server.notfound = notfound;
  
    return function notfoundLayer (req, res) {
      res.statusCode = 404;
      var matched = null;
      var cbindex = -1;
      for (var i = 0; i < regexes.length; i++) {
        matched = req.path.match (regexes[i]);
        if (matched !== null) { cbindex = i; break; }
      }
      if (cbindex >= 0) {
        catchpath(req, res, matched, callbacks[cbindex], server.templateReader);
      } else {
        res.end('Not Found\n');
      }
    };
  }
docs: Not Fount unit — in fact, mostly a copy&paste of the route unit.