    * @param _key - the key to resolve, or null
    * @return the value stored under the key, or the next value from an array
    */
-  mutating func value(forKey: String) -> Any?
+  func value(forKey: String) -> Any?
 }


  // MARK: - Value Handlers
  
  struct KeyValueHandler : KeyValueStringFormatterValueHandler {
    let lastKeyWasMiss = false
    let object : Any?
    

    }
  }
  
  final class ArrayValueHandler : KeyValueStringFormatterValueHandler {
    var lastKeyWasMiss = false
    let array  : [ Any? ]
    var cursor : Int = 0
