完善_parse_yolo_label_file函数的文档字符串，添加参数和返回值说明

utils/fed_util.py

@@ -25,6 +25,10 @@ def _parse_yolo_label_file(label_path: str) -> Set[int]:
     Return a set of class_ids found in a YOLO .txt label file.
     Empty file -> empty set. Missing file -> empty set.
     Robust to blank lines / trailing spaces.
+    Args:
+        label_path: path to the label file
+    Returns:
+        set of class IDs (integers) found in the file
     """
     class_ids: Set[int] = set()
     if not os.path.exists(label_path):