code: def _sample_directions(self):
      # Samples a direction vector (list of arrays with the same shapes as
      # input arrays and parameters)
      device = self.device
      xs = self.xs
      params = self.params
      no_gxs = self.no_gxs
  
      xp = device.xp
      direction_xs_shapes = [
          None if x is None else x.shape
          for x, no_gx in six.moves.zip(xs, no_gxs)
          if not no_gx
      ]
      direction_param_shapes = [p.shape for p in params]
      direction_shapes = direction_xs_shapes + direction_param_shapes
  
      total_size = sum(
          [
              int(numpy.prod(shape))
              for shape in direction_shapes
              if shape is not None
          ]
      )
  
      # Sample the concatenated vector at random
      directions = self._sample_unit_vector(total_size, xp)
  
      # Unpack the concatenated vector and returns as a list of arrays.
      return self._unpack_arrays(xp, directions, direction_shapes)
  
imports: from __future__ import absolute_import
  import warnings
  import numpy
  import six
  import chainer
  from chainer import backend
  from chainer.backends import _cpu
  from chainer.backends import cuda
  from chainer import configuration
  from chainer import testing
  from chainer import utils
  from chainer import variable
  import chainerx
label_desc: Use image node_id 5 for calling the _CheckBackward obj's underlying member method code with example usage: obj._sample_directions() and returns: self