code: def det_identity(self, gpu=False):
      if self.batched:
          chk = numpy.ones(len(self.x), dtype=self.dtype)
          dt = numpy.identity(self.x.shape[1], dtype=self.dtype)
          idt = numpy.repeat(dt[None], len(self.x), axis=0)
      else:
          idt = numpy.identity(self.x.shape[1], dtype=self.dtype)
          chk = numpy.ones(1, dtype=self.dtype)
      if gpu:
          chk = cuda.to_gpu(chk)
          idt = cuda.to_gpu(idt)
      idtv = chainer.Variable(idt)
      idtd = self.det(idtv)
      testing.assert_allclose(
          idtd.data, chk, **self.check_forward_options
      )
  
imports: import unittest
  import numpy
  import six
  import chainer
  from chainer.backends import cuda
  from chainer import functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  from chainer.utils import type_check
label_desc: Use image node_id 8 for calling the DetFunctionTest obj's underlying member method code with example usage: obj.det_identity(gpu) without return types