[MNT] modify typing in ABLModel

abl/learning/abl_model.py

@@ -91,7 +91,7 @@ class ABLModel:
         score = self.classifier_list[0].score(X=data_X, y=data_Y)
         return score
 
-    def train(self, X: List[List[Any]], Y: List[Any]):
+    def train(self, X: List[List[Any]], Y: List[Any]) -> float:
         """
         Train the model on the given data.
 
@@ -104,7 +104,7 @@ class ABLModel:
         """
         data_X, _ = self.merge_data(X)
         data_Y, _ = self.merge_data(Y)
-        self.classifier_list[0].fit(X=data_X, y=data_Y)
+        return self.classifier_list[0].fit(X=data_X, y=data_Y)
 
     @staticmethod
     def merge_data(X):