code: def save_to_disk(self, filename):
      dy.save(filename, [self.builder, self.lookup, self.R, self.bias])
  
file_path: dynet/examples/rnnlm/rnnlm.py
imports: import dynet
  import time
  import random
  from collections import defaultdict
  from itertools import count
  import argparse
  import sys
  import util
label_desc: Use image node_id 2 for calling the RNNLanguageModel obj's underlying member method code with example usage: obj.save_to_disk(filename) without return types