 }
 
 func difference<T: CollectionType where T.Generator.Element: Equatable>(a: T, _ b: T) -> [T.Generator.Element] {
-    return transform(a, b) { (var c, a, b, e) in
+    return transform(a, b) { (c, a, b, e) in
         if !b.contains(e) {
             c.append(e)
         }

// MARK: Hashids protocol

public protocol HashidsGenerator {
    typealias Char
    
    func encode(value: Int64...) -> String?
    

        return ret
    }
    
    private func _hash(inout hash: [Char], number: Int64, alphabet: [Char]) {
        let length = alphabet.count, index = hash.count
        var number = number
        repeat {
            hash.insert(alphabet[Int(number % Int64(length))], atIndex: index)
            number = number / Int64(length)
