code: def det_product(self, gpu=False):
      if gpu:
          cx = cuda.to_gpu(self.x)
          cy = cuda.to_gpu(self.y)
      else:
          cx = self.x
          cy = self.y
      vx = chainer.Variable(cx)
      vy = chainer.Variable(cy)
      dxy1 = self.det(self.matmul(vx, vy))
      dxy2 = self.det(vx) * self.det(vy)
      testing.assert_allclose(
          dxy1.data, dxy2.data, **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 11 for calling the DetFunctionTest obj's underlying member method code with example usage: obj.det_product(gpu) without return types