No need to unsafeify keyPath
Copy keyPath
Rename actual and objectValue to lastValue and proxySet, respectively
Dont name used variables _
Remove RACPropertySubscribingExamples itShouldBehaveLike block from +rac_signalWithChangesFor:keyPath:options:observer:
s/to.beTruthy/notTo.beNil
Change ordered sets to arrays in NSKeyValueObservingOptionPrior test
Amend rac_signalFor: docs