Note that Set has become a core class since Ruby 4.0

Development of this gem repository has ended and feature requests
and bug reports should be directed to bugs.ruby-lang.org.

See https://bugs.ruby-lang.org/issues/21216 for details.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hsbt

README.md

@@ -1,5 +1,7 @@
 # Set
 
+**Note:** As of Ruby 4.0, `Set` has become a core class (see [Feature #21216](https://bugs.ruby-lang.org/issues/21216)). Development of this gem repository has ended. Please report feature requests and bug reports at [bugs.ruby-lang.org](https://bugs.ruby-lang.org/).
+
 This library provides the Set class, which deals with a collection of
 unordered values with no duplicates.  It is a hybrid of Array's
 intuitive inter-operation facilities and Hash's fast lookup.