Enforces the TXT record maximum length of 255 characters.
    TXT record length includes key, value, and '='.

    :param str key: Key of the TXT record
    :param str value: Value of the TXT record

    :rtype: str
    :return: The value of the TXT record. It may be truncated if it exceeds
             the maximum permitted length. In case of truncation, '...' is
             appended to indicate that the entire value is not present.

def _enforce_txt_record_maxlen(key, value):
    '''
    Enforces the TXT record maximum length of 255 characters.
    TXT record length includes key, value, and '='.

    :param str key: Key of the TXT record
    :param str value: Value of the TXT record

    :rtype: str
    :return: The value of the TXT record. It may be truncated if it exceeds
             the maximum permitted length. In case of truncation, '...' is
             appended to indicate that the entire value is not present.
    '''
    # Add 1 for '=' seperator between key and value
    if len(key) + len(value) + 1 > 255:
        # 255 - 3 ('...') - 1 ('=') = 251
        return value[:251 - len(key)] + '...'
    return value