class_docstr: Base class for packing the parsed annotation info to MMOCR format.
  
  Args:
      data_root (str): The root path of the dataset.  It is usually set auto-
          matically and users do not need to set it manually in config file
          in most cases.
      split (str): The split of the dataset. It is usually set automatically
          and users do not need to set it manually in config file in most
          cases.
      nproc (int): Number of processes to process the data. Defaults to 1.
          It is usually set automatically and users do not need to set it
          manually in config file in most cases.
code: def __call__(self, samples) -> Dict:
      samples = track_parallel_progress(
          self.pack_instance, samples, nproc=self.nproc
      )
      samples = self.add_meta(samples)
      return samples
  
imports: from abc import abstractmethod
  from typing import Dict, List, Tuple
  from mmengine import track_parallel_progress
label_desc: Use image node_id 4 for calling the BasePacker obj's underlying member method code with example usage: obj.__call__(samples) and returns: samples