diff --git a/ch12.jl b/ch12.jl
index d848c81..bd1fe91 100644
--- a/ch12.jl
+++ b/ch12.jl
@@ -203,6 +203,7 @@ for type in [0, 1], col in ["deg_ml", "deg_web"]
 end
 
 gdf = groupby(classes_df, :ml_target)
+
 combine(gdf,
         :deg_ml => mean => :mean_deg_ml,
         :deg_web => mean => :mean_deg_web)