Update comments and simplify all_day check
Update comments and simplify all_day check

proevo/pythondotorg,python/pythondotorg,Mariatta/pythondotorg,manhhomienbienthuy/pythondotorg,proevo/pythondotorg,manhhomienbienthuy/pythondotorg,python/pythondotorg,proevo/pythondotorg,Mariatta/pythondotorg,proevo/pythondotorg,Mariatta/pythondotorg,manhhomienbienthuy/pythondotorg,python/pythondotorg,Mariatta/pythondotorg,python/pythondotorg,manhhomienbienthuy/pythondotorg