code: def add_neighbor(self, nei_node):
      self.neighbors.append(nei_node)
  
file_path: DIG/dig/ggraph/method/JTVAE/fast_jtnn/mol_tree.py
imports: import os
  import rdkit
  import rdkit.Chem
  from tqdm import tqdm
  from .chemutils import get_clique_mol, tree_decomp, get_mol, get_smiles, set_atommap, enum_assemble, decode_stereo
  from .vocab import *
  import argparse
label_desc: Use image node_id 2 for calling the MolTreeNode obj's underlying member method code with example usage: obj.add_neighbor(nei_node) without return types