message: Prepare 0.3.4 release.
diff: @@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
  and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
  ## [Unreleased]
  +
  +## [0.3.4] - 2017-12-20
  - Handle optional and rest parameters in function type expressions.
  ## [0.3.3] - 2017-12-18
  