code: function catchpath (req, res, pathmatch, callback, templateReader) {
    getQueries(req, function gotQueries(err) {
      if (err != null) {
        log('While getting queries for ' + req.uri + ':\n'
          + err
          , 'error');
      } else {
        // params: template parameters (JSON-serializable).
        callback(req.query, pathmatch, function end (params, options) {
          options = options || {};
          var templates = options.template || pathmatch[0];
          var reader = options.reader || templateReader;
          if (Object(options.string) instanceof String) {
            templates = [streamFromString(options.string)];
          } else if (Object(params) instanceof String) {
            templates = [streamFromString(params)];
          } else if (!Array.isArray(templates)) {
            templates = [templates];
          }
          if (!res.getHeader('Content-Type')  // Allow overriding.
              && (Object(templates[0]) instanceof String)) {
            res.mime(p.extname(templates[0]).slice(1));
          }
          for (var i = 0; i < templates.length; i++) {
            if (Object(templates[i]) instanceof String) {
              // `templates[i]` is a string path for a file.
              var templatePath = p.join(req.server.documentRoot, templates[i]);
              templates[i] = fs.createReadStream(templatePath);
            }
          }
  
          var template = concatStreams(templates);
  
          template.on('error', function(err) {
            log(err.stack, 'error');
            res.end('Not Found\n');
          });
  
          if (params === null || reader === null) {
            // No data was given. Same behaviour as static.
            template.pipe(res);
          } else {
            reader(template, res, params, function errorcb(err) {
              if (err) {
                log(err.stack, 'error');
                res.end('Not Found\n');
              }
            });
          }
        }, req.ask);
      }
    });
  }
docs: Route *and* not found units — see what I did there?