class_docstr: Leaf and constituent children are mixed in the same node
class_docstr_tok: ["Leaf","and","constituent","children","are","mixed","in","the","same","node"]
code: def __init__(self, line_num, child_label, children):
      super().__init__(
          "Found a tree with both text children and bracketed children!  Line number {}  Child label {}  Children {}".format(
              line_num, child_label, children
          )
      )
      self.line_num = line_num
      self.child_label = child_label
      self.children = children
  
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 MixedTreeError object from inherited base classes: ValueError with example: obj = MixedTreeError(line_num, child_label, children)