code: def copy_submission_to_destination(self, src_filename, dst_subdir,
                                       submission_id):
      
  
      extension = [e for e in ALLOWED_EXTENSIONS if src_filename.endswith(e)]
      if len(extension) != 1:
        logging.error('Invalid submission extension: %s', src_filename)
        return
      dst_filename = os.path.join(self.target_dir, dst_subdir,
                                  submission_id + extension[0])
      cmd = ['gsutil', 'cp', src_filename, dst_filename]
      if subprocess.call(cmd) != 0:
        logging.error('Can\'t copy submission to destination')
      else:
        logging.info('Submission copied to: %s', dst_filename)
docs: Copies submission to target directory.
  
      Args:
        src_filename: source filename of the submission
        dst_subdir: subdirectory of the target directory where submission should
          be copied to
        submission_id: ID of the submission, will be used as a new
          submission filename (before extension)