code: def call_func_function(self, backend_config, x1):
      forward_xp, backward_xp = _get_expected_xp(backend_config, True)
  
      class Func(chainer.Function):
          def forward(self, inputs):
              # Inputs
              assert isinstance(inputs, tuple)
              (x1,) = inputs
              assert isinstance(x1, forward_xp.ndarray)
  
              y2 = x1 * 3 + 2
              self.retain_inputs(())
              self.retain_outputs(
                  (
                      1,
                      2,
                  )
              )
              return None, y2, None
  
          def backward(self, inputs, grad_outputs):
              # Retained inputs
              assert isinstance(inputs, tuple)
              (x1,) = inputs
              assert x1 is None
  
              # Output gradients
              assert isinstance(grad_outputs, tuple)
              gy1, gy2, gy3 = grad_outputs
              assert gy1 is None
              assert isinstance(gy2, backward_xp.ndarray)
              assert gy3 is None
  
              # Retained outputs
              output_data = self.output_data
              assert isinstance(output_data, tuple)
              assert len(output_data) == 3
              y1, y2, y3 = output_data
              assert y1 is None
              assert isinstance(y2, backward_xp.ndarray)
              assert y3 is None
  
              gx1 = 3 * gy2
              return (gx1,)
  
      return Func()(x1)
  
imports: import unittest
  import numpy
  import chainer
  from chainer import testing
  import chainer.testing.backend
  import chainerx
label_desc: Use image node_id 1 for calling the TestFunctionOutputNone obj's underlying member method code with example usage: obj.call_func_function(backend_config, x1) and returns: Func, None,  y2,  None, gx1