State Management (Abstract class)

Hi.

Can you help me please ? I would like to know :

  1. Abstract class leaves the implementation to subclass. Code will be safe, honest… Why exactly ?

  2. A subclass implements an abstract class. Why don’t we use class MemoryRepository implements Repository instead of class MemoryRepository extends Repository in the book? What’s the difference ?

Ps: I think I will find my answer for question 1 in Dart book. (I will buy it after reading flutter book …)