public class MyBatchable implements Iterator<Integer>, Iterable<Integer>, Database.Batchable<Integer>, Database.Stateful, Database.AllowsCallouts {
    @TestVisible Integer remainingCount = 5000;
    public integer next() {
        return remainingCount--;
    }
    public boolean hasNext() {
        return remainingCount > 0;
    }
    public iterator<integer> iterator() {
        return this;
    }
    public Iterator<Integer> start(Database.BatchableContext bc) {
        return this;
    }
    public void execute(Database.BatchableContext bc, Integer[] values) {
        // Do your stuff here
        // If you run out of stuff to do, System.abortJob(bc.getJobId());
    }
    public void finish(Database.BatchableContext bc) {
        // Be sure to reset remainingCount if you need to process more data,
        // or you'll enter an infinite batch loop.
        // You can call another Database.executeBatch(this, 1); here if you need more processing.
    }
}