code: def check_forward(self, x_data, y_data):
      x = chainer.Variable(x_data)
      y = chainer.Variable(y_data)
      if self.out_len == 1:
          z = functions.forget(lambda x, y: (x + y + x,), x, y)
          testing.assert_allclose(x_data + y_data + x_data, z.data)
      elif self.out_len == 2:
          z = functions.forget(lambda x, y: (x + y + x, x * y), x, y)
          testing.assert_allclose(x_data + y_data + x_data, z[0].data)
          testing.assert_allclose(x_data * y_data, z[1].data)
  
imports: import functools
  import unittest
  import numpy
  import six
  import chainer
  from chainer import cuda
  from chainer import functions
  from chainer import gradient_check
  from chainer import links
  from chainer import testing
  from chainer.testing import attr
  from chainer import variable
label_desc: Use image node_id 2 for calling the TestForget obj's underlying member method code with example usage: obj.check_forward(x_data, y_data) without return types