class_docstr: List column, for debug.
class_docstr_tok: ["List","column",",","for","debug","."]
code: def get(self):
      if len(self._q) == self._index:
          return Empty()
      self._index += 1
      return copy.deepcopy(self._q[self._index - 1])
  
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 2 for calling the _ListColumn obj's underlying member method code with example usage: obj.get() and returns: copy, Empty