docs: def _ref_replacer(match, passage):
      """ Helper to replace xpath/scope/refsDecl on iteration with passage value
  
      :param match: A RegExp match
      :type match: re.SRE_MATCH
      :param passage: A list with subreference informations
      :type passage: iter
  
      :rtype: basestring
      :return: Replaced string
      """
      groups = match.groups()
      ref = next(passage)
      if ref is None:
          return groups[0]
      else:
          return "{1}='{0}'".format(ref, groups[0])