class_docstr: A tree had no label, such as ((Foo) (Bar))
  
  This does not actually happen at the root, btw, as ROOT is silently added
class_docstr_tok: ["A","tree","had","no","label",",","such","as","(","(","Foo",")","(","Bar",")",")","This","does","not","actually","happen","at","the","root",",","btw",",","as","ROOT","is","silently","added"]
code: def __init__(self, line_num):
      super().__init__(
          "Found a tree with no label on a node!  Line number %d"
          % line_num
      )
      self.line_num = line_num
  
imports: from collections import deque
  import logging
  import os
  import re
  from stanza.models.constituency.parse_tree import Tree
  from stanza.utils.get_tqdm import get_tqdm
label_desc: Use image node_id 1 to create a new UnlabeledTreeError object from inherited base classes: ValueError with example: obj = UnlabeledTreeError(line_num)