facebook/immutable-js — pull request #126 by DavidTimms (2014-10-06 17:37:55+00:00)
Title: Modified flatten to return an IndexedSequence

I noticed than flatten was returning a basic sequence, rather than an indexed sequence, which contradicted the type definition, so I made a little tweak to clear that up. The __iterate method of flattened sequences was returning the wrong count too, which was causing some subtle bugs.

I've added tests for the stuff I changed.