docs: static Selector convertSet(Selector expr, List set) {
      Selector ans = null;
      for (int i = 0; i < set.size(); i++) {
        Selector comparand = (Selector) set.get(i);
        Selector comparison = new OperatorImpl(Operator.EQ, (Selector) expr.clone(), comparand);
        if (ans == null)
          ans = comparison;
        else
          ans = new OperatorImpl(Operator.OR, ans, comparison);
      }
      return ans;
    }