目的：避免static变量是个文件内可见的全局变量
Get：
std::atomic<bool>* GetGraphVerboseStepLr() {
static std::atomic<bool> graph_verbose_step_lr{
false};
return &graph_verbose_step_lr;
}
Set：
void SetGraphVerboseStepLr(bool verbose) {
auto* graph_verbose_step_lr = GetGraphVerboseStepLr();
*graph_verbose_step_lr = verbose;
}
调用：
inline Maybe<void> SetVerbose(bool verbose) {
SetGraphVerboseStepLr(verbose);
return Maybe<void>::Ok();
}
inline bool GetVerbose() {
return *GetGraphVerboseStepLr(); }