code: def forward(self, inputs, device):
      x, indices = inputs
      y = functions.permutate(x, indices, axis=self.axis, inv=self.inv)
      return (y,)
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import functions
  from chainer import testing
  from chainer.testing import attr
  from chainer.utils import force_array
label_desc: Use image node_id 3 for calling the TestPermutate obj's underlying member method code with example usage: obj.forward(inputs, device) and returns: y