diff --git a/src/labelme2yolo/l2y.py b/src/labelme2yolo/l2y.py
index 0be1d1f..850e177 100644
--- a/src/labelme2yolo/l2y.py
+++ b/src/labelme2yolo/l2y.py
@@ -28,6 +28,7 @@ NUM_THREADS = max(1, os.cpu_count() - 1)
 
 
 def train_test_split(dataset_index, test_size=0.2):
+    """Split dataset into train set and test set with test_size"""
     test_size = min(max(0.0, test_size), 1.0)
     total_size = len(dataset_index)
     train_size = int(math.ceil(total_size * (1.0 - test_size)))
@@ -332,8 +333,8 @@ class Labelme2YOLO:
         if shape['label'] in self._label_id_map:
             label_id = self._label_id_map[shape['label']]
             return label_id, yolo_center_x, yolo_center_y, yolo_w, yolo_h
-        else:
-            raise f"label {shape['label']} not in {self._label_list}"
+
+        raise f"label {shape['label']} not in {self._label_list}"
 
     def _get_other_shape_yolo_object(self, shape, img_h, img_w):
 
@@ -350,8 +351,8 @@ class Labelme2YOLO:
         if shape['label'] in self._label_id_map:
             label_id = self._label_id_map[shape['label']]
             return label_id, points.tolist()
-        else:
-            raise f"label {shape['label']} not in {self._label_list}"
+
+        raise f"label {shape['label']} not in {self._label_list}"
 
     def _save_dataset_yaml(self):
         yaml_path = os.path.join(