}
 
    if (arity > 3) {
      return next_layer();
    }
 
    try {
      layer.handle(req, res, next_layer);
    } catch (err) {
      next_layer(err);

    }
 
    try {
      layer.handle(req, res, next_layer);
    } catch (err) {
      next_layer(err);
    }
  })();
};
 

      // this should be done for the layer
      return self.process_params(layer, req, res, function(err) {
        if (err) {
          return next(err);
        }
 
        if (route) {
          return layer.handle(req, res, next);
        }
        trim_prefix();

  var params = this.params;
 
  // captured parameters from the route, keys and values
  var keys = route.keys;
 
  // fast track
  if (!keys || keys.length === 0) {
    return done();
  }
 

          options.push.apply(options, route._options());
        }
      }
 
      req.params = layer.params;
 
      // this should be done for the layer
      return self.process_params(layer, req, res, function(err) {
        if (err) {
          return next(err);

      if (err || options.length === 0) return old(err);
 
      var body = options.join(',');
      return res.set('Allow', body).send(body);
    });
  }
 
  next();
 
  function next(err) {

 * @api public
 */
 
var proto = module.exports = function(options) {
  options = options || {};
 
  function router(req, res, next) {
    router.handle(req, res, next);
  }
 

      if (err) {
        if (arity === 4) {
          layer.handle(err, req, res, next);
        } else {
          next(err);
        }
      } else if (arity < 4) {
        layer.handle(req, res, next);
      } else {
        next(err);

        if (err) {
          return next(err);
        }
 
        if (route) {
          return layer.handle(req, res, next);
        }
        trim_prefix();
      });