code: def build_eval_path(self, epoch, iteration):
          
          if iteration is not None:
              eval_fname = f'eval_epoch_{epoch}_iter_{iteration}'
          else:
              eval_fname = f'eval_epoch_{epoch}'
          eval_path = os.path.join(self.save_path, eval_fname)
          return eval_path
docs: Appends index of the current epoch and index of the current iteration
          to the name of the file with results.
  
          :param epoch: index of the current epoch
          :param iteration: index of the current iteration