Replaces unzip for extracting a single element with map.

Before:

Seq((1, 11), (2, 22)).unzip._1
Seq((1, 11, 111), (2, 22, 222)).unzip3._1

After:
Seq((1, 11), (2, 22)).map(_._1)
Seq((1, 11, 111), (2, 22, 222)).map(_._1)