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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def rst_to_html(in_rst, stderr):
 """Renders HTML from an RST fragment. :param string in_rst: An rst formatted string. :param stderr: An open stream to use for docutils stderr output. :returns: A tuple of (html rendered rst, return code) """

  if not in_rst:
    return '', 0

  # Unfortunately, docutils is really setup for command line use.
  # We're forced to patch the bits of sys its hardcoded to use so that we can call it in-process
  # and still reliably determine errors.
  # TODO(John Sirois): Move to a subprocess execution model utilizing a docutil chroot/pex.
  orig_sys_exit = sys.exit
  orig_sys_stderr = sys.stderr
  returncodes = []
  try:
    sys.exit = returncodes.append
    sys.stderr = stderr
    pp = publish_parts(in_rst,
                       writer_name='html',
                       # Report and exit at level 2 (warnings) or higher.
                       settings_overrides=dict(exit_status_level=2, report_level=2),
                       enable_exit_status=True)
  finally:
    sys.exit = orig_sys_exit
    sys.stderr = orig_sys_stderr

  return_value = ''
  if 'title' in pp and pp['title']:
    return_value += '<title>{0}</title>\n<p style="font: 200% bold">{0}</p>\n'.format(pp['title'])
  return_value += pp['body'].strip()
  return return_value, returncodes.pop() if returncodes else 0