code: def extract(self, destination, format='csv', csv_delimiter=None, csv_header=True, compress=False):
      
      job = self.extract_async(destination, format=format, csv_delimiter=csv_delimiter,
                               csv_header=csv_header, compress=compress)
      if job is not None:
        job.wait()
      return job
docs: Exports the table to GCS; blocks until complete.
  
      Args:
        destination: the destination URI(s). Can be a single URI or a list.
        format: the format to use for the exported data; one of 'csv', 'json', or 'avro'
            (default 'csv').
        csv_delimiter: for CSV exports, the field delimiter to use. Defaults to ','
        csv_header: for CSV exports, whether to include an initial header line. Default true.
        compress: whether to compress the data on export. Compression is not supported for
            AVRO format. Defaults to False.
      Returns:
        A Job object for the completed export Job if it was started successfully; else None.