a simple asynchronous queue
npm install then-queue
var Queue = ;var q = ;
A fresh queue!
Push an item onto the queue
queue.pop() -> Promise Item
Pop an item from the queue
Amount of items in the queue (note that this can be negative if
pop has been called more times than
length-changed event gets emitted whenever
push has been called. You could use it to spawn/kill workers when the length changes.