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
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