Few things in Duolingo have sparked as much debate as its heart system. Make too many mistakes, and you’d be locked out of lessons unless you waited, practiced old material, or paid up. Learners argued this discouraged experimentation and punished the very thing language learning requires: making mistakes. Now, Duolingo has rolled out a new mechanic... The post Duolingo Energy System – The Complete Guide appeared first on duoplanet.| duoplanet
Understand Java Generics' super and extends| Gary Gregory