code: def forward(self, x):
      return (x[0],)
  
file_path: chainer/tests/chainer_tests/testing_tests/test_unary_math_function_test.py
imports: import unittest
  from chainer import function_node
  from chainer import testing
label_desc: Use image node_id 2 for calling the DummyLinear obj's underlying member method code with example usage: obj.forward(x) and returns: x