private void putOnList(Varnode output, long offset, ArrayList<PointerRef> todoList,
			HashSet<Varnode> doneList) {
		if (doneList.contains(output)) {
			return;
		}
		todoList.add(new PointerRef(output, offset));
		doneList.add(output);
	}
Add a Varnode reference to the current work list to facilitate flow tracing.
To prevent cycles, a separate of visited Varnodes is maintained
@param output is the Varnode at the current point of flow
@param offset is the relative offset of the Varnode to the root variable
@param todoList is the current work list
@param doneList is the visited list
Ghidra/Features/Decompiler/src/main/java/ghidra/app/decompiler/util/FillOutStructureHelper.java