class_docstr: Nose Plugin that supports doctests in extension modules.
      
code: def options(self, parser, env=os.environ):
      Plugin.options(self, parser, env)
      parser.add_option(
          "--doctest-tests",
          action="store_true",
          dest="doctest_tests",
          default=env.get("NOSE_DOCTEST_TESTS", True),
          help="Also look for doctests in test modules. "
          "Note that classes, methods and functions should "
          "have either doctests or non-doctest tests, "
          "not both. [NOSE_DOCTEST_TESTS]",
      )
      parser.add_option(
          "--doctest-extension",
          action="append",
          dest="doctestExtension",
          help="Also look for doctests in files with "
          "this extension [NOSE_DOCTEST_EXTENSION]",
      )
      # Set the default as a list, if given in env; otherwise
      # an additional value set on the command line will cause
      # an error.
      env_setting = env.get("NOSE_DOCTEST_EXTENSION")
      if env_setting is not None:
          parser.set_defaults(doctestExtension=tolist(env_setting))
  
imports: import doctest
  import inspect
  import logging
  import os
  import re
  import sys
  from testpath import modified_env
  from inspect import getmodule
  from doctest import REPORTING_FLAGS, REPORT_ONLY_FIRST_FAILURE, _unittest_reportflags, DocTestRunner, _extract_future_flags, pdb, _OutputRedirectingPdb, _exception_traceback, linecache
  from nose.plugins import doctests, Plugin
  from nose.util import anyp, tolist
  from IPython.utils.py3compat import builtin_mod, PY3, getcwd
label_desc: Use image node_id 1 for calling the ExtensionDoctest obj's underlying member method code with example usage: obj.options(parser, env) without return types