class_docstr: The Tree object factorize a constituency tree into four fields, each associated with one or more :class:`Field` objects.
  
  Attributes:
      WORD:
          Words in the sentence.
      POS:
          Part-of-speech tags, or underscores if not available.
      TREE:
          The raw constituency tree in :class:`nltk.tree.Tree` format.
      CHART:
          The factorized sequence of binarized tree traversed in pre-order.
class_docstr_tok: ["The","Tree","object","factorize","a","constituency","tree","into","four","fields",",","each","associated","with","one","or","more",":","class",":","`","Field","`","objects",".","Attributes",":","WORD",":","Words","in","the","sentence",".","POS",":","Part-of-speech","tags",",","or","underscores","if","not","available",".","TREE",":","The","raw","constituency","tree","in",":","class",":","`","nltk.tree.Tree","`","format",".","CHART",":","The","factorized","sequence","of","binarized","tree","traversed","in","pre-order","."]
code: def tgt(self):
      return (self.CHART,)
  
imports: from collections.abc import Iterable
  import nltk
  from tqdm import tqdm
  from underthesea.utils.sp_parallel import is_master
label_desc: Use image node_id 3 for calling the Tree obj's underlying member method code with example usage: obj.tgt() and returns: self