diff --git a/src/utils/qdf/blacklist.rs b/src/utils/qdf/blacklist.rs
index d7e8f80..09d0246 100644
--- a/src/utils/qdf/blacklist.rs
+++ b/src/utils/qdf/blacklist.rs
@@ -22,21 +22,41 @@ impl Blacklist {
     }
 }
 
-/// Apply a blacklist to a Quantamental DataFrame with Lazy API.
+/// Apply a blacklist to a Quantamental DataFrame.
 ///
 /// * `blacklist` is a map from any “ticker‑like” key to a tuple of
 ///   `(start_date, end_date)` in **inclusive** `"YYYY‑MM‑DD"` format.
 /// * `metrics` – if `None`, every metric from `get_unique_metrics(df)`
 ///   is used.
-/// * `group_by_cid = Some(false)` is not implemented yet (parity with
-///   the eager version).
-pub fn apply_blacklist_lazy(
+/// * `group_by_cid = Some(false)` is not implemented yet.
+pub fn apply_blacklist(
     df: &mut DataFrame,
     blacklist: &BTreeMap<String, (String, String)>,
     metrics: Option<Vec<String>>,
     group_by_cid: Option<bool>,
 ) -> Result<DataFrame, Box<dyn std::error::Error>> {
     check_quantamental_dataframe(df)?;
+    // dataframe is like:
+    // | cid | xcat | real_date | metric1 | metric2 |
+    // |-----|------|-----------|---------|---------|
+    // | A   | B    | 2023-01-01| 1.0     | 2.0     |
+    // | A   | B    | 2023-01-02| 1.0     | 2.0     |
+    // | A   | C    | 2023-01-01| 1.0     | 2.0     |
+    // | A   | C    | 2023-01-02| 1.0     | 2.0     |
+    // | D   | E    | 2023-01-01| 1.0     | 2.0     |
+    // | D   | E    | 2023-01-02| 1.0     | 2.0     |
+
+    // (real date column is Naive date)
+
+    // blacklist is like:
+    // {'A_B_1': ('2023-01-02', '2023-01-03'),
+    //  'A_B_2': ('2023-01-04', '2023-01-05'),
+    //  'A_C_1': ('2023-01-02', '2023-01-03'), }
+
+    // get_cid('A_B_1') = 'A'
+    // get_cid('A_B_2') = 'A'
+    // get_cid('D_E_1') = 'D'
+
     Ok(df.clone())
 }
 /// Create a blacklist from a Quantamental DataFrame.