added Cubix link

Author: Steve Krouse

episodes/30.md

@@ -24,6 +24,7 @@ James Koppel is a Carnegie Mellon CS grad, Thiel Fellow, entrepreneur, educator,
 * [Daikon](http://pgbovine.net/publications/daikon-invariant-detector_SCP-2007.pdf) - dynamic detection of likely invariants
 * [Semantic designs](http://www.semdesigns.com/)
 * [Ira Baxter](http://www.semdesigns.com/Company/People/idbaxter/)
+* [Cubix](https://github.com/jkoppel/cubix/)
 * [On understanding data abstraction, revisited](https://www.cs.utexas.edu/~wcook/Drafts/2009/essay.pdf)
 * [The power of interoperability, why objects are inevitable](https://www.cs.cmu.edu/~aldrich/papers/objects-essay.pdf)
 * [Program slicing](https://en.wikipedia.org/wiki/Program_slicing)