code: def string(self):
      sep = "" if self.indent_amount is None else "\n"
      return sep.join(self.html)
  
imports: import abc
  import argparse
  import contextlib
  import difflib
  import enum
  import glob
  import itertools
  import json
  import nbformat
  import os.path
  import re
  import subprocess
  import sys
  import textwrap
label_desc: Use image node_id 4 for calling the HtmlBuilder obj's underlying member method code with example usage: obj.string() and returns: sep