Hello! Welcome to the 28th session of the Python Master Course. In the previous Lesson 27, we mastered decorators. This time, it's context managers. In Lesson 16, we learned the 'with open(...) as f:' ...

Task 2 Memory Management Simulation Pending C/C++ or Python Virtual memory paging system, Page replacement (FIFO, LRU), Page fault & hit/miss analysis Task 3 File System Operations & Security Pending ...

# photo 级并发由 _photo_semaphore 控制（默认 3），包裹整段 photo 下载（见 download_by_photo_detail）。