Creates a dynamic remarketing campaign.

  Args:
    client: an AdWordsClient instance.
    campaign_id: an int campaign ID.

  Returns:
    The ad group that was successfully created.

def CreateAdGroup(client, campaign_id):
  """Creates a dynamic remarketing campaign.

  Args:
    client: an AdWordsClient instance.
    campaign_id: an int campaign ID.

  Returns:
    The ad group that was successfully created.
  """
  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]