diff --git a/image_prediction/image_extractor/extractors/parsable.py b/image_prediction/image_extractor/extractors/parsable.py
index 056679b..d852e8d 100644
--- a/image_prediction/image_extractor/extractors/parsable.py
+++ b/image_prediction/image_extractor/extractors/parsable.py
@@ -146,6 +146,9 @@ def make_maybe_image_metadata_pair(image: Either, metadata: Either):
     # return Right(make_image_metadata_pair).amap(image).amap(metadata).either(left(context), right(identity))
 
     # 3)
+    # a := Image
+    # b := Metadata
+    # c := ImageMetadataPair
     return (
         image.bind(right(make_image_metadata_pair))  # m a >>= m (a -> b -> c) -> m (b -> c)
         .amap(metadata)  # m (b -> c) <*> m b -> m c