Method set_accu_var

common/expr.h:750–750

  }

  void set_accu_var(std::string accu_var) { accu_var_ = std::move(accu_var); }

  void set_accu_var(absl::string_view accu_var) {
    accu_var_.assign(accu_var.data(), accu_var.size());