message: fixed python3.5 format
diff: @@ -143,7 +143,7 @@ class RBMClassification(xacc.Algorithm):
  n_steps_past = steps_per_epoch*n_epochs_past
  if n_steps_past < prev_last_step:
  - checkpoint.restore(f'{checkpoint_prefix}-{n_steps_past}')
  + checkpoint.restore('{}'.format(checkpoint_prefix-n_steps_past))
  print('Starting from checkpoint {}.'.format(n_steps_past))
  dataset, n_evts = make_dataset_train(
  @@ -178,9 +178,9 @@ class RBMClassification(xacc.Algorithm):
  dataexp_h, modexp_h
  )
  if i % 10 == 0:
  - LOGGER.debug(f'weight updates: {W_delta}')
  - LOGGER.debug(f'visible bias updates: {bv_delta}')
  - LOGGER.debug(f'hidden bias updates: {bh_delta}')
  + LOGGER.debug('weight updates: {}'.format(W_delta))
  + LOGGER.debug('visible bias updates: {}'.format(bv_delta))
  + LOGGER.debug('hidden bias updates: {}'.format(bh_delta))
  W.assign((1 - l2reg) * W + lr * W_delta)
  bv.assign((1 - l2reg) * bv + lr * bv_delta)
  