sgf-parsing: add explicit args

Author: lpalma

exercises/sgf-parsing/src/Sgf.hs

@@ -5,4 +5,4 @@ import Data.Text (Text)
 import Data.Tree (Tree)
 
 parseSgf :: Text -> Maybe (Tree (Map Text [Text]))
-parseSgf = error "You need to implement this function."
+parseSgf sgf = error "You need to implement this function."