 
 public extension Dictionary {
 
+  /**
+   - Parameter name: The name of the property that you want to map
+   - Returns: A generic type if casting succeeds, otherwise it throws
+   */
   func propertyOrThrow<T>(name: String) throws -> T {
     guard let key = name as? Key,
       value = self[key] as? T

    return value
  }

  func property<T>(name: String) -> T? {
    guard let key = name as? Key,
      value = self[key] as? T

    return value
  }

  /**
   - Parameter name: The name of the property that you want to map
   - Parameter transformer: A transformation closure
   - Returns: A generic type if casting succeeds, otherwise it returns nil
   */
  func transform<T, U>(name: String, transformer: ((value: U?) -> T?)) -> T? {
    guard let value = self[name as! Key] else { return nil }
    return transformer(value: value as? U)
  }

  /**
   - Parameter name: The name of the property that you want to map
   - Returns: A mappable object, otherwise it returns nil
   */
  func relation<T : Mappable>(name: String) -> T? {
    guard let value = self[name as! Key],
      dictionary = value as? JSONDictionary
