class_docstr: Class which encapsulates logit of the master.
docstr: Reads dataset metadata.
  
  Returns:
    instance of DatasetMetadata
code: def _read_dataset_metadata(self):
      """Reads dataset metadata.
  
      Returns:
        instance of DatasetMetadata
      """
      blob = self.storage_client.get_blob(
          "dataset/" + self.dataset_name + "_dataset.csv"
      )
      buf = BytesIO()
      blob.download_to_file(buf)
      buf.seek(0)
      return eval_lib.DatasetMetadata(buf)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import argparse
  import collections
  from collections import defaultdict
  import csv
  from io import BytesIO
  import logging
  import os
  import pickle
  import random
  import time
  from six import iteritems
  from six import iterkeys
  from six import itervalues
  from six.moves import input
  import eval_lib
label_desc: Use image node_id 7 for calling the EvaluationMaster obj's underlying member method code with example usage: obj._read_dataset_metadata() and returns: eval_lib