code: public boolean disjointTypes(List<Type> ts, List<Type> ss) {
          while (ts.tail != null && ss.tail != null) {
              if (disjointType(ts.head, ss.head)) return true;
              ts = ts.tail;
              ss = ss.tail;
          }
          return false;
      }
docs: <editor-fold defaultstate="collapsed" desc="disjointTypes">