code: def CreateAdGroup(client, campaign_id):
    
    ad_group_service = client.GetService('AdGroupService', 'v201809')
  
    ad_group = {
        'name': 'Dynamic remarketing ad group',
        'campaignId': campaign_id,
        'status': 'ENABLED'
    }
  
    operations = [{
        'operator': 'ADD',
        'operand': ad_group
    }]
  
    return ad_group_service.mutate(operations)['value'][0]
docs: Creates a dynamic remarketing campaign.
  
    Args:
      client: an AdWordsClient instance.
      campaign_id: an int campaign ID.
  
    Returns:
      The ad group that was successfully created.