empty implementation of abstract base class method

image_prediction/formatter/formatters/enum.py

@@ -4,6 +4,9 @@ from image_prediction.formatter.formatters.key_formatter import KeyFormatter
 
 
 class EnumFormatter(KeyFormatter):
-    @staticmethod
-    def format_key(key):
+
+    def format_key(self, key):
         return key.value if isinstance(key, Enum) else key
+
+    def transform(self, obj):
+        raise NotImplementedError