code: def check_forward(self, s_data, i_data):
      xp = backend.get_array_module(s_data)
      s_old = s_data.copy()
      s = chainer.Variable(s_data)
      i = chainer.Variable(i_data)
      x, t = thin_stack.thin_stack_get(s, i)
  
      expect = s_old[xp.arange(len(i_data)), i_data]
      testing.assert_allclose(x.array, expect)
  
      # Thin stack reuses the same ndarray.
      self.assertIs(s_data, t.array)
  
imports: import unittest
  import numpy
  import chainer
  from chainer import backend
  from chainer import cuda
  from chainer import testing
  from chainer.testing import attr
  import thin_stack
label_desc: Use image node_id 2 for calling the TestThinStackGet obj's underlying member method code with example usage: obj.check_forward(s_data, i_data) without return types