Usage:

function jobHandler(jobs){

	// in this example, jobs is an array of size 1-3
	jobs.forEach(function(job){

		// job {
		// 	  item:    XXX,
		// 	  resolve: function,
		// 	  reject:  function,
		// 	  promise: Promise
		// }

		if (job.item > 10) {
			job.resolve('this number is greater than 10');
		}

		// use job.reject() to fail a job
		// any jobs not resolved after any returned promises have resolved, will automatically be rejected
		
	});
}

var batchThisJob = cargo(jobHandler, {size: 3, delay: 200});

batchThisJob(563);
batchThisJob(75);
batchThisJob(2);
// jobHandler([...])
batchThisJob(43);
// jobHandler([...]) // (after 200 ms)