code: def flat_module(x):
      def unit(i, prefix):
          c1 = PF.convolution(
              i, 4, (3, 3), pad=(1, 1), name=prefix + "-c1"
          )
          c2 = PF.convolution(
              F.relu(c1), 4, (3, 3), pad=(1, 1), name=prefix + "-c2"
          )
          c = F.add2(c2, c1, inplace=True)
          return c
  
      c = unit(x, "c1")
      c2 = unit(c, "c2")
      y = PF.affine(c2, 5, name="fc")
      return y
  
imports: import pytest
  import numpy
  import nnabla
  import nnabla.functions
  import nnabla.parametric_functions
  from nnabla.testing import assert_allclose
  from helper import get_saved_test_model, forward_variable_and_check_equal, forward_variable, assert_topology, dump_network_topology
  import legacy_nnp_graph
  from nnabla.utils import nnp_graph
label_desc: Use image node_id 1 for calling a global function with example usage: flat_module(x) and returns: y, c