hasNil (operate on optional array)

/**
 * Asserter
 */
extension Array {
   /**
    * Asserts if array has nil values
    * ## Examples:
    * let someArr: [Int?] = [1,2,nil]
    * someArr.hasNil() // true
    * [1,2,2].hasNil() // false
    */
   public func hasNil<T>() -> Bool where Element == T? {
      self.contains { $0 == nil }
   }
}