docs: def _getAdmlDisplayName(adml_xml_data, display_name):
      '''
      helper function to take the 'displayName' attribute of an element and find
      the value from the ADML data
  
      adml_xml_data :: XML data of all ADML files to search
      display_name :: the value of the displayName attribute from the ADMX entry
                      to search the ADML data for
      '''
      if display_name.startswith('$(') and display_name.endswith(')'):
          display_name = re.sub(r'(^\$\(|\)$)', '', display_name)
          display_name = display_name.split('.')
          displayname_type = display_name[0]
          displayname_id = display_name[1]
          search_results = ADML_DISPLAY_NAME_XPATH(adml_xml_data,
                                                   displayNameType=displayname_type,
                                                   displayNameId=displayname_id)
          if search_results:
              for result in search_results:
                  return result.text
  
      return None