code: def forward_expected(self, inputs):
      (x,) = inputs
      y_expected = numpy.pad(
          x,
          self.pad_width,
          mode=self.mode,
          constant_values=self.constant_values,
      )
      return (y_expected,)
  
file_path: chainer/tests/chainer_tests/functions_tests/array_tests/test_pad.py
imports: import numpy
  from chainer import functions
  from chainer import testing
label_desc: Use image node_id 3 for calling the TestPad obj's underlying member method code with example usage: obj.forward_expected(inputs) and returns: y_expected