code: def forward_expected(self, inputs):
      y = numpy.concatenate(inputs, self.axis)
      return (y,)
  
file_path: chainer/tests/chainer_tests/functions_tests/array_tests/test_concat.py
imports: import unittest
  import numpy
  from chainer import functions
  from chainer import testing
  from chainer.testing import backend
label_desc: Use image node_id 3 for calling the TestConcat obj's underlying member method code with example usage: obj.forward_expected(inputs) and returns: y