Start with rate function.

src/lib.rs

@@ -35,11 +35,18 @@ impl Default for Rating {
     }
 }
 
+fn rate(rating_groups: &[&[Rating]]) {
+    let ranks = (0..rating_groups.len()).collect::<Vec<_>>();
+    let weights = vec![1.0; rating_groups.len()];
+    let min_delta = DELTA;
+}
+
 fn quality(rating_groups: &[&[Rating]]) -> f32 {
     let flatten_ratings = rating_groups
         .iter()
         .flat_map(|group| group.iter())
         .collect::<Vec<_>>();
+
     let flatten_weights = vec![1.0; flatten_ratings.len()].into_boxed_slice();
 
     let length = flatten_ratings.len();