code: def test_backend(self):
      self.assertIn(readline.backend, ("readline", "editline"))
  
imports: import locale
  import os
  import sys
  import tempfile
  import textwrap
  import unittest
  from test.support import verbose
  from test.support.import_helper import import_module
  from test.support.os_helper import unlink, temp_dir, TESTFN
  from test.support.pty_helper import run_pty
  from test.support.script_helper import assert_python_ok
label_desc: Use image node_id 2 for calling the TestReadline obj's underlying member method code with example usage: obj.test_backend() without return types