class_docstr: Base class for tuning job or training job analytics classes.
  
  Understands common functionality like persistence and caching.
docstr: Sub-class must calculate the dataframe and return it.
docstr_tok: ["Sub-class","must","calculate","the","dataframe","and","return","it","."]
code: def _fetch_dataframe(self):
      """Sub-class must calculate the dataframe and return it."""
  
imports: from __future__ import print_function, absolute_import
  from abc import ABCMeta, abstractmethod
  from collections import defaultdict, OrderedDict
  import datetime
  import logging
  from six import with_metaclass
  from sagemaker.session import Session
  from sagemaker.utils import DeferredError
  from sagemaker.lineage import artifact
label_desc: Use image node_id 4 for calling the AnalyticsMetricsBase obj's underlying member method code with example usage: obj._fetch_dataframe() without return types