private static void dedupVarnodes(ArrayList<Varnode> varlist) {
		if (varlist.size() < 2) {
			return;
		}
		ArrayList<Varnode> resList = new ArrayList<>();
		HashSet<Varnode> hashSet = new HashSet<>();
		for (Varnode vn : varlist) {
			if (hashSet.add(vn)) {
				resList.add(vn);
			}
		}
		varlist.clear();
		varlist.addAll(resList);
	}
Encode a particular PcodeOp and slot
@param op is the PcodeOp to preserve
@param slot is the slot to preserve (-1 for output, >=0 for input)
@param method is the method to use for encoding (4, 5, or 6)
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/pcode/DynamicHash.java