class_docstr: List column, for debug.
class_docstr_tok: ["List","column",",","for","debug","."]
code: def __init__(self):
      self._q = []
      self._index = 0
  
imports: import threading
  import copy
  from enum import Enum, auto
  from typing import List, Tuple, Union, Dict, Optional
  from collections import deque, namedtuple
label_desc: Use image node_id 1 to create a new _ListColumn object  with example: obj = _ListColumn()