code: function(data, callback) {
  		var set = _assembleTask(data, workFlow[meth][url].merg);
  		if (set.err) throw new Error('Invalid workflow: ' + set.tasks);
  		async.series(set.tasks, function(err, results) {
  			return callback(err, {
  				'sync': data.sync,
  				'async': data.async,
  				'merg': results
  			});
  		});
  	}
docs: Merg - Parallel process
  @param  {Object}   data - return values of sync and async
  @param  {Function} callback