code: def _get_annotation_path(self, annotation_id):
      return os.path.join(
          self._get_split_path(),
          "{}.{}".format(annotation_id, self._annotation_type),
      )
  
file_path: luminoth/luminoth/tools/dataset/readers/object_detection/flat_reader.py
imports: import json
  import os
  import six
  import tensorflow
  from PIL import Image
  from luminoth.tools.dataset.readers import InvalidDataDirectory
  from luminoth.tools.dataset.readers.object_detection import ObjectDetectionReader
  from luminoth.utils.dataset import read_image
label_desc: Use image node_id 7 for calling the FlatReader obj's underlying member method code with example usage: obj._get_annotation_path(annotation_id) and returns: os