JetBrains/kotlin — pull request #371 by Stebalien (2014-02-12 16:47:46+00:00)
Title: Add an intention to simplify negated expressions.

Given an expression of the form `!(a op b)`, replace it with `a !op b`.

From | To
----------|----------
!(a in b) | a !in b
!(a is b) | a !is b
!(a == b) | a != b
!(a != b) | a == b
!(a >= b) | a < b
!(a > b) | a <= b
!(a <= b) | a > b
!(a < b) | a >= b

Notes:
* This intention could probably be named better ("Push Not In" is awkward) but I can't think of a better (accurate) name.