         return self.seconds
     }
     
+    // MARK: - Validation
+    
     func isEven() -> Bool {
         return (self % 2) == 0
     }

import Foundation

public extension Int {
    
    var years: NSTimeInterval {
        return 365 * self.days

    func isNegative() -> Bool {
        return !isPositive()
    }
    
    // MARK: - Instance Methods
    
    func split() -> [Int] {
        var result = [Int]()
