class_docstr_tok: []
docstr_tok: []
code: def __init__(self, io_loop: IOLoop) -> None:
      """ """
      self._group = _CallbackGroup(io_loop)
  
imports: from __future__ import annotations
  import logging
  from typing import TYPE_CHECKING, Callable, Sequence
  from ..core.types import ID
  from ..util.tornado import _CallbackGroup
label_desc: Use image node_id 1 to create a new DocumentCallbackGroup object  with example: obj = DocumentCallbackGroup(io_loop)