code: def call_func(self, backend_config, x1):
      if self.function_node:
          return self.call_func_function_node(backend_config, x1)
      else:
          return self.call_func_function(backend_config, x1)
  
imports: import unittest
  import numpy
  import chainer
  from chainer import testing
  import chainer.testing.backend
  import chainerx
label_desc: Use image node_id 3 for calling the TestFunctionOutputNone obj's underlying member method code with example usage: obj.call_func(backend_config, x1) and returns: self, self