@Override
	public CodeBlockReference next() throws CancelledException {
    	monitor.checkCancelled();
    	return (blockRefQueue.isEmpty() ? null : blockRefQueue.removeFirst());
    }
@see ghidra.program.model.block.CodeBlockReferenceIterator#next()
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/block/SubroutineSourceReferenceIterator.java