Repetition stats

src/lang.rs

@@ -392,4 +392,8 @@ impl CardSet {
     fn history_len(&self) -> usize {
         return min(MAX_HISTORY_LEN, (self.set.len() as f32 * MAX_HISTORY_LEN_PART) as usize);
     }
+
+    pub fn len(&self) -> usize {
+        self.set.len()
+    }
 }