code: def check_forward(self, xs):
      y = chainerrl.functions.sum_arrays(xs)
      correct_y = sum(self.xs)
      gradient_check.assert_allclose(correct_y, cuda.to_cpu(y.array))
  
file_path: chainerrl/tests/functions_tests/test_sum_arrays.py
imports: import unittest
  import numpy
  import chainer
  from chainer import cuda
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  import chainerrl
label_desc: Use image node_id 2 for calling the TestSumArrays obj's underlying member method code with example usage: obj.check_forward(xs) without return types