code: function safeCall (fn, args, callback) {
    args = Array.prototype.slice.call(arguments, 1);
    callback = args.pop();
    var callbackCalled;
  
    try {
      args.push(safeCallback);
      fn.apply(null, args);
    }
    catch (err) {
      if (callbackCalled) {
        throw err;
      }
      else {
        safeCallback(err);
      }
    }
  
    function safeCallback (err, result) {
      if (callbackCalled) {
        err = ono('Error in %s: callback was called multiple times', fn.name);
      }
  
      callbackCalled = true;
      callback(err, result);
    }
  }
docs: Calls the specified function with the given arguments, ensuring that the callback
  is only called once, and that it's called even if an unhandled error occurs.
  
  @param {function} fn - The function to call
  @param {...*} [args] - The arguments to pass to the function
  @param {function} callback - The callback function