class_docstr: Utility class for conversation metadata.
  
  Metadata should be saved at ``<datapath>.metadata``.
code: def __init__(self, datapath):
      self._load(datapath)
  
imports: import datetime
  import json
  import os
  import itertools
  from parlai.utils.io import PathManager
  from parlai.core.metrics import dict_report
  from parlai.utils.misc import AttrDict
  import parlai.utils.logging
label_desc: Use image node_id 1 to create a new Metadata object  with example: obj = Metadata(datapath)