code: def forward(self, inputs, device):
      (x,) = inputs
      y = functions.pad(
          x,
          self.pad_width,
          mode=self.mode,
          constant_values=self.constant_values,
      )
      return (y,)
  
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 4 for calling the TestPad obj's underlying member method code with example usage: obj.forward(inputs, device) and returns: y