This content was released on Sep 20 2018. The official support period is 6-months from this date.
Swift 4.2 refined some of the syntax dealing with finding the first instance of an item in a collection, as well as some new ones to find the last instance.
This is a companion discussion topic for the original entry at https://www.kodeco.com/7490-what-s-new-in-swift-4-2-new-sequence-methods