mozilla/rust — pull request #8023 by blake2-ppc (2013-07-24 15:43:15+00:00)
Title: Implement DoubleEndedIterator for FlatMapIterator

This PR includes the changes from pull #7931 which add a useful method to Option.

Make .flat_map_() double-ended if the base iterator and the mapped-to iterator type are both double-ended.