code: def check_forward(self, x, grid, expected):
      y = functions.spatial_transformer_sampler(x, grid)
      testing.assert_allclose(y.data, expected)
  
imports: import unittest
  import numpy
  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.testing import condition
  from chainer import Variable
label_desc: Use image node_id 2 for calling the TestSpatialTransformerSamplerForwardPaddedImage obj's underlying member method code with example usage: obj.check_forward(x, grid, expected) without return types