code: def to_dot(nodes):
      lines = [
          "digraph GraphName {",
          "node [shape=rect];",
          "rankdir=LR;",
      ]
      for i, n in enumerate(nodes):
          lines.append(
              f'{i} [label={escape(n.label)}, color={ "red" if n.root else "black"}];'
          )
  
      for i, f in enumerate(nodes):
          for label, j in f.referrents:
              lines.append(f"{i} -> {j} [label = {escape(label)}]")
      lines.append("}\n")
      return "\n".join(lines)
  
imports: import gc
  import sys
  from typing import Any, Dict, List, NamedTuple, Optional, Tuple
  import types
  import weakref
  import json
  from tempfile import NamedTemporaryFile
  import torch
  from torch.cuda._memory_viz import _frames_fmt, _block_extra
  import atexit
  import logging
label_desc: Use image node_id 9 for calling a global function with example usage: to_dot(nodes) and returns: str