class_docstr: Proxy for DocTestCase: provides an address() method that
  returns the correct address for the doctest case. Otherwise
  acts as a proxy to the test case. To provide hints for address(),
  an obj may also be passed -- this will be used as the test object
  for purposes of determining the test address, if it is provided.
code: def runTest(self):
      test = self._dt_test
      runner = self._dt_runner
  
      old = sys.stdout
      new = StringIO()
      optionflags = self._dt_optionflags
  
      if not (optionflags & REPORTING_FLAGS):
          # The option flags don't include any reporting flags,
          # so add the default reporting flags
          optionflags |= _unittest_reportflags
  
      try:
          # Save our current directory and switch out to the one where the
          # test was originally created, in case another doctest did a
          # directory change.  We'll restore this in the finally clause.
          curdir = getcwd()
          # print 'runTest in dir:', self._ori_dir  # dbg
          os.chdir(self._ori_dir)
  
          runner.DIVIDER = "-" * 70
          failures, tries = runner.run(
              test, out=new.write, clear_globs=False
          )
      finally:
          sys.stdout = old
          os.chdir(curdir)
  
      if failures:
          raise self.failureException(
              self.format_failure(new.getvalue())
          )
  
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 2 for calling the DocTestCase obj's underlying member method code with example usage: obj.runTest() without return types