code: def _get_left_image_id(left_image):
      """Returns the id of an image file.
  
      Used to associate an image file with its corresponding label.
      Example:
        'bonn_000001_000019_leftImg8bit' -> 'bonn_000001_000019'
  
      Args:
        left_image: name of the image file.
  
      Returns:
        Id of the image (see example above).
      """
      match = LEFT_IMAGE_FILE_RE.match(left_image)
      return "{}_{}_{}".format(*match.groups())
  
file_path: datasets/tensorflow_datasets/datasets/cityscapes/cityscapes_dataset_builder.py
imports: import os
  import re
  from tensorflow_datasets.core.utils.lazy_imports_utils import tensorflow
  import tensorflow_datasets.public_api
label_desc: Use image node_id 1 for calling a global function with example usage: _get_left_image_id(left_image) and returns: str