class_docstr: Client wrapper to access Google Cloud Datastore.
docstr: Starts transaction.
docstr_tok: ["Starts","transaction","."]
code: def transaction(self):
      """Starts transaction."""
      return self._client.transaction()
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import logging
  import math
  import random
  import time
  import traceback
  from google.cloud import datastore
  from google.cloud import storage
  from google.cloud.exceptions import TooManyRequests
label_desc: Use image node_id 6 for calling the CompetitionDatastoreClient obj's underlying member method code with example usage: obj.transaction() and returns: self