title: Ambiguous reference to member 'decode(_:forKey:)' swift4
body: <p>I am parsing a response that needs to be transformed from a dictionary on the server (which is a legacy data format) - to simply an array of strings on the client side. Therefore I am wanting to decode the key called 'data' as a dictionary, so i can iterate through the keys and create an array of strings on the client side.</p>
  
  <pre><code>init(from decoder: Decoder) throws  {
    let values = try decoder.container(keyedBy: CodingKeys.self)
    do {
      let some_data_dictionary = try values.decode([String:Any].self, forKey: CodingKeys.data)
  
      for (kind, values) in some_data_dictionary {
        self.data_array.append(kind)  
      }
    } catch {
      print("we could not get 'data' as [String:Any] in legacy data \(error.localizedDescription)")
    }
  }
  </code></pre>
  
  <p>The error I am getting is: <code>Ambiguous reference to member 'decode(_:forKey:)'</code></p>