code: def fetch_groups(groups):
      
      hidden_groups = current_app.config.get(
          'OAUTHCLIENT_CERN_HIDDEN_GROUPS', OAUTHCLIENT_CERN_HIDDEN_GROUPS)
      hidden_groups_re = current_app.config.get(
          'OAUTHCLIENT_CERN_HIDDEN_GROUPS_RE',
          OAUTHCLIENT_CERN_HIDDEN_GROUPS_RE)
      groups = [group for group in groups if group not in hidden_groups]
      filter_groups = []
      for regexp in hidden_groups_re:
          for group in groups:
              if regexp.match(group):
                  filter_groups.append(group)
      groups = [group for group in groups if group not in filter_groups]
  
      return groups
docs: Prepare list of allowed group names.
  
      :param groups: The complete list of groups.
      :returns: A filtered list of groups.