C# 15: Closed hierarchies

Closed hierarchies on one page: mark a family closed, switch with no default arm, and when to choose a union instead. From the blog post [What's new in C# 15: Closed hierarchies](/blog/whats-new-in-csharp-15-closed-hierarchies).

Updated

The cheat sheet C# 15: Closed hierarchies, with Codey: the three points of the post on one page
Category
C#
Level
Apprentice
Tags
csharp, csharp-15, whats-new