private Operator findO(I I, ArrayList<O> Oids){
        
        for(O O:Oids){
            if(O.id.equals(I.id)){
                return O;
            }
        }
        
        Operator curr = I.next;
        
        while(curr != null){
            if(curr.type == Operator.Type.O && I.id.equals(curr.id)){
                return curr;
            }
            curr = curr.next;
        }
        
        return null;
    }