   }
 }
 
-extension _CocoaDictionary {
-  @usableFromInline
-  @_effects(releasenone)
-  internal func key(for index: Index) -> AnyObject {
-    return index.allKeys[index.currentKeyIndex]
-  }
-}
-
 extension _CocoaDictionary: Equatable {
   @usableFromInline
   internal static func ==(


  @inlinable
  @inline(__always)
  func lookup(_ index: Index) -> (key: Key, value: Value) {
    _precondition(hashTable.isOccupied(index),
      "Attempting to access Dictionary elements using an invalid Index")


    @inlinable
    public subscript(position: Index) -> Element {
      return _variant.key(at: position)
    }

    // Customization
