code: def CreateDefaultPartition(client, ad_group_id):
    
    ad_group_criterion_service = client.GetService('AdGroupCriterionService',
                                                   version='v201809')
  
    operations = [{
        'operator': 'ADD',
        'operand': {
            'xsi_type': 'BiddableAdGroupCriterion',
            'adGroupId': ad_group_id,
            # Make sure that caseValue and parentCriterionId are left unspecified.
            # This makes this partition as generic as possible to use as a
            # fallback when others don't match.
            'criterion': {
                'xsi_type': 'ProductPartition',
                'partitionType': 'UNIT'
            },
            'biddingStrategyConfiguration': {
                'bids': [{
                    'xsi_type': 'CpcBid',
                    'bid': {
                        'microAmount': 500000
                    }
                }]
            }
        }
    }]
  
    ad_group_criterion = ad_group_criterion_service.mutate(operations)['value'][0]
  
    print ('Ad group criterion with ID "%d" in ad group with ID "%d" was added.'
           % (ad_group_criterion['criterion']['id'],
              ad_group_criterion['adGroupId']))
docs: Creates a default partition.
  
    Args:
      client: an AdWordsClient instance.
      ad_group_id: an integer ID for an ad group.