code: def _average_2d(xs):
      xs = sum(xs, [])
      return sum(xs) / len(xs)
  
file_path: chainer/chainermn/extensions/observation_aggregator.py
imports: from __future__ import division
  from chainer.training import extension, util
  from chainer import Variable
  import chainerx
label_desc: Use image node_id 1 for calling a global function with example usage: _average_2d(xs) and returns: unknown