@Override
	public Varnode getRef(int id) {
		if (refmap == null) {
			return null;
		}
		return refmap.get(id);
	}
return all PcodeOps associated with a particular instruction Address
@param addr -- Address of instruction generating PcodeOps
@return -- Iterator to PcodeOps
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/pcode/PcodeSyntaxTree.java