code: def test_func_wo_source_code(self):
      code = "def f_exec():\n  return 1"
      # Use `exec` to generate a function without source code
      exec(code, globals())  # pylint: disable=exec-used
      txt = free_vars_detect.generate_free_var_logging(
          f_exec
      )  # pylint: disable=undefined-variable
      self.assertIsNone(txt)
  
imports: import functools
  import unittest
  from absl.testing import parameterized
  import numpy
  from tensorflow.core.function.capture import free_vars_detect
  from tensorflow.python.util import tf_decorator
label_desc: Use image node_id 4 for calling the GenerateLoggingTest obj's underlying member method code with example usage: obj.test_func_wo_source_code() without return types