code: def _within_bracket(toks):
      label = next(toks)
      children = []
      for tok in toks:
          if tok == "(":
              children.append(_within_bracket(toks))
          elif tok == ")":
              return Tree(label, children)
          else:
              children.append(Tree(tok, None))
      raise RuntimeError("Error Parsing sexpr string")
  
imports: import re
  import codecs
  import random
  from collections import Counter
label_desc: Use image node_id 4 for calling a global function with example usage: _within_bracket(toks) and returns: Tree