code: def append(self, datum, label, label_plain, comment):
      self.data_list.append(datum)
      self.label_list.append(label)
      self.label_list_plain.append(label_plain)
      self.comment_list.append(comment)
      return len(self.data_list)
  
file_path: attention-ocr/aocr/util/bucketdata.py
imports: from __future__ import absolute_import
  import numpy
label_desc: Use image node_id 2 for calling the BucketData obj's underlying member method code with example usage: obj.append(datum, label, label_plain, comment) and returns: len