code: def _untag(self, tree):
      for i, child in enumerate(tree):
          if isinstance(child, Tree):
              self._untag(child)
          elif isinstance(child, tuple):
              tree[i] = child[0]
          else:
              raise ValueError("expected child to be Tree or tuple")
      return tree
  
imports: import codecs
  import os.path
  import nltk
  from nltk.chunk import tagstr2tree
  from nltk.corpus.reader.api import *
  from nltk.corpus.reader.bracket_parse import BracketParseCorpusReader
  from nltk.corpus.reader.util import *
  from nltk.tokenize import *
  from nltk.tree import Tree
label_desc: Use image node_id 3 for calling the ChunkedCorpusView obj's underlying member method code with example usage: obj._untag(tree) and returns: tree