What is this directory

This directory is an inherent part of the framework. API design from the client (user) perspective is done here.

Why is this directory needed?

Top-Down, Outside-In Design

This directory is an inherent part of the framework. API design from the client (user) perspective is done here. All framework implementation should start here, whether by a framework product designer or a framework implementor, but holding the perspective of the user of the framework—not that of its implementor.

In the limit, no framework implementation work should start without the client code design done here first.