Hi!

I figured out that this condition is unnecessary, so we can just use ```return [result firstObject]``` (I've commited this changes)

For ```first``` method we should add ```import NSArray+ObjectiveSugar.h```. I think it's unnecessary, because of this methods are equal.  As you can see current implementation of NSMutableArray+ObjectiveSugar.m uses ```lastObject```, not ```last```.