code: def _get_device(device_spec):
      # Converts device specificer to a chainer.Device instance.
      # Additionally to chainer.get_device, this function supports None
      if device_spec is None:
          return None
      return backend.get_device(device_spec)
  
imports: import collections
  import numpy
  import six
  import chainer
  from chainer import backend
  from chainer.backends import cuda
label_desc: Use image node_id 4 for calling a global function with example usage: _get_device(device_spec) and returns: backend, None