code: def test_callback(self):
      k = [None]
      v = [None]
  
      def callback(key):
          k.append(key)
          v.append(cf.get_option(key))
  
      cf.register_option("d.a", "foo", cb=callback)
      cf.register_option("d.b", "foo", cb=callback)
  
      del k[-1], v[-1]
      cf.set_option("d.a", "fooz")
      assert k[-1] == "d.a"
      assert v[-1] == "fooz"
  
      del k[-1], v[-1]
      cf.set_option("d.b", "boo")
      assert k[-1] == "d.b"
      assert v[-1] == "boo"
  
      del k[-1], v[-1]
      cf.reset_option("d.b")
      assert k[-1] == "d.b"
  
imports: import pytest
  from pandas._config import config
  from pandas._config.config import OptionError
  import pandas
  import pandas._testing
label_desc: Use image node_id 18 for calling the TestConfig obj's underlying member method code with example usage: obj.test_callback() without return types