code: def save(self, checkpoint_path_prefix, current_step):
      checkpoint_path = "{0}-{1}".format(
          checkpoint_path_prefix,
          current_step,
      )
  
      assert workspace.RunOperatorOnce(
          core.CreateOperator(
              "Save",
              self.model.GetAllParams(),
              [],
              absolute_path=True,
              db=checkpoint_path,
              db_type="minidb",
          )
      )
  
      checkpoint_config_path = os.path.join(
          os.path.dirname(checkpoint_path_prefix),
          "checkpoint",
      )
      with open(checkpoint_config_path, "w") as checkpoint_config_file:
          checkpoint_config_file.write(
              'model_checkpoint_path: "' + checkpoint_path + '"\n'
              'all_model_checkpoint_paths: "' + checkpoint_path + '"\n'
          )
          logger.info("Saved checkpoint file to " + checkpoint_path)
  
      return checkpoint_path
  
imports: import argparse
  import collections
  import logging
  import math
  import numpy
  import random
  import time
  import sys
  import os
  import caffe2.proto.caffe2_pb2
  from caffe2.python import core, workspace, data_parallel_model
  import caffe2.python.models.seq2seq.seq2seq_util
  from caffe2.python.models.seq2seq.seq2seq_model_helper import Seq2SeqModelHelper
label_desc: Use image node_id 19 for calling the Seq2SeqModelCaffe2 obj's underlying member method code with example usage: obj.save(checkpoint_path_prefix, current_step) and returns: checkpoint_path