class_docstr: XML dataset for detection.
  
  Args:
      img_subdir (str): Subdir where images are stored. Default: JPEGImages.
      ann_subdir (str): Subdir where annotations are. Default: Annotations.
      backend_args (dict, optional): Arguments to instantiate the
          corresponding backend. Defaults to None.
docstr: Return the sub data root.
docstr_tok: ["Return","the","sub","data","root","."]
code: def sub_data_root(self) -> str:
      """Return the sub data root."""
      return self.data_prefix.get("sub_data_root", "")
  
file_path: mmdetection/mmdet/datasets/xml_style.py
imports: import os.path
  import xml.etree.ElementTree
  from typing import List, Optional, Union
  import mmcv
  from mmengine.fileio import get, get_local_path, list_from_file
  from mmdet.registry import DATASETS
  from .base_det_dataset import BaseDetDataset
label_desc: Use image node_id 2 for calling the XMLDataset obj's underlying member method code with example usage: obj.sub_data_root() and returns: self