code: def _nullcontext():
      """Pre-Python-3.7-compatible standin for contextlib.nullcontext."""
      yield
  
imports: import contextlib
  from tensorboard import data_compat
  from tensorboard import dataclass_compat
  from tensorboard.compat import tf
  from tensorboard.compat.proto import event_pb2
  from tensorboard.util import platform_util
  from tensorboard.util import tb_logging
label_desc: Use image node_id 1 for calling a global function with example usage: _nullcontext() without return types