code: function (/*message, channel*/) {
          var args = Array.prototype.slice.apply(arguments);
          var message = args[0];
  
          var rpcCallbackHandler = function () {};
  
          
  
          // Check if event is of type "rpc".
          if ('__type' in message && message.__type === 'rpc') {
              // After the application executes the "done" handler,
              // the result will be trigger back to the "back channel" (rpc response).
              // After that step, the "rpc callback" handler will handle the result data.
              rpcCallbackHandler = function (err, result) {
                  self.emit(
                      message.__backChannel,
                      {
                          err: err,
                          result: result
                      }
                  );
              };
          }
  
          // Append our extended rpc callback handler
          args = [].concat(args, [rpcCallbackHandler]);
  
          // Call original handler with extended args
          handler.apply(null, args);
      }
docs: Wrap the original event handler.
  
  Argument params:
  
  @param {Object} message
  @param {String} channel
  @param {Function} rpc this rpc callback handler will be added by this function