code: def forward(self, inputs, device):
      (x,) = inputs
      function = getattr(functions, self.function_name)
      y = function(x, axis=self.axis)
      y = functions.cast(y, numpy.int64)
      return (y,)
  
imports: import unittest
  import numpy
  import chainer
  from chainer import functions
  from chainer import testing
  from chainer import utils
label_desc: Use image node_id 2 for calling the TestArgMinMax obj's underlying member method code with example usage: obj.forward(inputs, device) and returns: y