code: def test_visit_block_postprocessing(self):
      class TestTransformer(transformer.Base):
          def _process_body_item(self, node):
              if isinstance(node, gast.Assign) and (
                  node.value.id == "y"
              ):
                  if_node = gast.If(
                      gast.Name(
                          "x",
                          ctx=gast.Load(),
                          annotation=None,
                          type_comment=None,
                      ),
                      [node],
                      [],
                  )
                  return if_node, if_node.body
              return node, None
  
          def visit_FunctionDef(self, node):
              node.body = self.visit_block(
                  node.body, after_visit=self._process_body_item
              )
              return node
  
      def test_function(x, y):
          z = x
          z = y
          return z
  
      tr = TestTransformer(self._simple_context())
  
      node, _ = parser.parse_entity(test_function, future_features=())
      node = tr.visit(node)
  
      self.assertEqual(len(node.body), 2)
      self.assertIsInstance(node.body[0], gast.Assign)
      self.assertIsInstance(node.body[1], gast.If)
      self.assertIsInstance(node.body[1].body[0], gast.Assign)
      self.assertIsInstance(node.body[1].body[1], gast.Return)
  
imports: import re
  import gast
  import unittest
  from nvidia.dali._autograph.pyct import anno
  from nvidia.dali._autograph.pyct import origin_info
  from nvidia.dali._autograph.pyct import parser
  from nvidia.dali._autograph.pyct import transformer
label_desc: Use image node_id 6 for calling the TransformerTest obj's underlying member method code with example usage: obj.test_visit_block_postprocessing() and returns: z, node,  None, node, if_node,  if_node