code: def __init__(self):
      super(DummyChain, self).__init__()
      with self.init_scope():
          self.l = chainer.links.Linear(None, 1)
  
file_path: chainer/tests/chainermn_tests/extensions_tests/test_observation_aggregator.py
imports: from __future__ import division
  import pytest
  import numpy
  import chainer
  import chainer.testing
  from chainer.training import extension
  from chainer.backend import cuda
  import chainermn
  from chainermn.testing import get_device
  from chainermn.extensions import ObservationAggregator
  import chainerx
label_desc: Use image node_id 1 to create a new DummyChain object from inherited base classes: chainer with example: obj = DummyChain()