code: def check_forward(self, x_data):
      x = chainer.Variable(x_data)
      y = self.func(x)
      testing.assert_allclose(
          self.np_func(self.x), y.data, atol=1e-4, rtol=1e-4
      )
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  import chainer.functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 2 for calling the TrigonometricFunctionsTest obj's underlying member method code with example usage: obj.check_forward(x_data) without return types