code: def check_backward(self, x, gy, ggW):
      return
  
      def f(x, gy):
          emb = embed_id.EmbedIDGrad(self.w_shape, self.ignore_label)
          return emb.apply((x, numpy.zeros(()), gy))[0]
  
      gradient_check.check_backward(f, (x, gy), (ggW,))
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer.functions.connection import embed_id
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import backend
label_desc: Use image node_id 2 for calling the TestEmbedIdGrad obj's underlying member method code with example usage: obj.check_backward(x, gy, ggW) and returns: emb