Method set_iter_var2

common/expr.h:714–716

  }

  void set_iter_var2(std::string iter_var2) {
    iter_var2_ = std::move(iter_var2);
  }

  void set_iter_var2(absl::string_view iter_var2) {
    iter_var2_.assign(iter_var2.data(), iter_var2.size());