code: private Batch getBatchForGraph() {
  		Batch lastValidBatch = this.batches.isEmpty() ? null : this.batches.get(this.batches.size()-1);
  		
  		if (lastValidBatch != null && lastValidBatch.graphSize() < this.maxBatchSize)
  			return lastValidBatch;
  		else {
  			Batch next = new Batch(this, this.mapper, this.accessToken, this.apiVersion, this.timeout, this.retries);
  			this.batches.add(next);
  			return next;
  		}
  	}
docs: Get an appropriate Batch for issuing a new graph call.  Will construct a new one
  if all existing batches are full.