code: def _get_bq_service(credentials=None, service_url=None):
      
  
      assert credentials, 'Must provide ServiceAccountCredentials'
  
      http = credentials.authorize(Http())
      service = build(
          'bigquery',
          'v2',
          http=http,
          discoveryServiceUrl=service_url,
          cache_discovery=False
      )
  
      return service
docs: Construct an authorized BigQuery service object.