public void printInstruction(Writer w) throws Exception {
        if(isDeleted()) {
            throw new Exception("Deleted instruction printed as part of CFG");
        }
	w.write(Integer.toString(number) + ": " + opcode.toString());

        if(color != null) {
            w.write(" " + color.toString() + " :=");
        }
	ArrayList<Value> args = getArguments();
	for(Value v : args) {
	    v.printAsArg(w);
	}
    }