docstr: 方便构建COCO()
docstr_tok: ["\u65b9\u4fbf\u6784\u5efaCOCO","(",")"]
code: def get_annotations(self, idx):
      """方便构建COCO()"""
      data = self.xmls_info[idx]
      h = int(data["size"]["height"])
      w = int(data["size"]["width"])
      target = self.objects_bboxes[idx]
      masks = self.parse_mask(idx)
      target["masks"] = masks
      return target, h, w
  
file_path: deep-learning-for-image-processing/pytorch_object_detection/mask_rcnn/my_dataset_voc.py
imports: import os
  import json
  from lxml import etree
  import numpy
  from PIL import Image
  import torch
  from torch.utils.data import Dataset
  from train_utils import convert_to_coco_api
label_desc: Use image node_id 6 for calling the VOCInstances obj's underlying member method code with example usage: obj.get_annotations(idx) and returns: target,  h,  w