NSSet+map.h

#import <Foundation/NSSet.h>

@interface NSSet (YOLOMap)

/**
 Invokes the given block once for each element of self. Creates a new
 array containing the values returned by the block.

    id rv = @[@1, @2, @3, @4].map(^(NSNumber *n){
        return @(n.intValue * n.intValue);
    });
    // rv => @[@1, @4, @9, @16]

 If the given block returns nil, that element is skipped in the returned
 array.

 The given block can have up to three parameters, the first is an element
 in the array, the second that element’s index, and the third the array
 itself.

 The second parameter can be a primitive (eg. `int`), or an `NSNumber *`:

    @"YOLO".split(@"").map(^(NSString *letter, int index){
        //…
    });
*/
- (NSSet *(^)(id block))map;

@end