message: Fix the assignment of `batch_loss`
diff: " \n",
  " optimizer.apply_gradients(zip(gradients, variables), tf.train.get_or_create_global_step())\n",
  " \n",
  - " batch_loss += (loss / int(targ.shape[1]))\n",
  + " batch_loss = (loss / int(targ.shape[1]))\n",
  " \n",
  " total_loss += batch_loss\n",
  " \n",
  