     */
     public func createClassifier(
         name: String,
-        classnamePositiveExamples: URL,
+        positiveExamples: [PositiveExample],
         negativeExamples: URL? = nil,
         failure: ((Error) -> Void)? = nil,
         success: @escaping (Classifier) -> Void)

    */
    public func updateClassifier(
        classifierID: String,
        classnamePositiveExamples: URL? = nil,
        negativeExamples: URL? = nil,
        failure: ((Error) -> Void)? = nil,
        success: @escaping (Classifier) -> Void)
    {
        // construct body
        let multipartFormData = MultipartFormData()
        if let classnamePositiveExamples = classnamePositiveExamples {
            multipartFormData.append(classnamePositiveExamples, withName: "classname_positive_examples")
        }
        if let negativeExamples = negativeExamples {
            multipartFormData.append(negativeExamples, withName: "negative_examples")

        let multipartFormData = MultipartFormData()
        let nameData = name.data(using: String.Encoding.utf8)!
        multipartFormData.append(nameData, withName: "name")
        positiveExamples.forEach { example in
            multipartFormData.append(example.examples, withName: example.name + "_positive_examples")
        }
        if let negativeExamples = negativeExamples {
            multipartFormData.append(negativeExamples, withName: "negative_examples")
        }
