Learning about semaphores Just one of the things I'm learning. https://github.com/hchiam/learning https://greenteapress.com/wp/semaphores https://github.com/AllenDowney/LittleBookOfSemaphores http://greenteapress.com/semaphores/threading_cleanup.py http://greenteapress.com/semaphores/counter.py