| // Returns a wrapper function that returns a wrapped callback | 
 | // The wrapper function should do some stuff, and return a | 
 | // presumably different callback function. | 
 | // This makes sure that own properties are retained, so that | 
 | // decorations and such are not lost along the way. | 
 | module.exports = wrappy | 
 | function wrappy (fn, cb) { | 
 |   if (fn && cb) return wrappy(fn)(cb) | 
 |  | 
 |   if (typeof fn !== 'function') | 
 |     throw new TypeError('need wrapper function') | 
 |  | 
 |   Object.keys(fn).forEach(function (k) { | 
 |     wrapper[k] = fn[k] | 
 |   }) | 
 |  | 
 |   return wrapper | 
 |  | 
 |   function wrapper() { | 
 |     var args = new Array(arguments.length) | 
 |     for (var i = 0; i < args.length; i++) { | 
 |       args[i] = arguments[i] | 
 |     } | 
 |     var ret = fn.apply(this, args) | 
 |     var cb = args[args.length-1] | 
 |     if (typeof ret === 'function' && ret !== cb) { | 
 |       Object.keys(cb).forEach(function (k) { | 
 |         ret[k] = cb[k] | 
 |       }) | 
 |     } | 
 |     return ret | 
 |   } | 
 | } |