code: def test_forward_cpu_nobias(self):
      self.check_forward(self.x, self.W, None)
  
imports: import unittest
  import numpy
  from six import moves
  from chainer import cuda
  from chainer.functions.connection import convolution_2d
  from chainer.functions.connection import local_convolution_2d
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import condition
label_desc: Use image node_id 4 for calling the TestLocalConvolution2DFunction obj's underlying member method code with example usage: obj.test_forward_cpu_nobias() without return types