How to use the letsencrypt.errors.ConfigurationError function in letsencrypt

.. todo:: fix hardcoded sites-enabled, check os.path.samefile

        :param str avail_fp: Complete file path of available site

        :returns: Success
        :rtype: bool

        """

        enabled_dir = os.path.join(self.parser.root, "sites-enabled")
        if not os.path.isdir(enabled_dir):
            error_msg = ("Directory '{0}' does not exist. Please ensure "
                         "that the values for --apache-handle-sites and "
                         "--apache-server-root are correct for your "
                         "environment.".format(enabled_dir))
            raise errors.ConfigurationError(error_msg)
        for entry in os.listdir(enabled_dir):
            try:
                if filecmp.cmp(avail_fp, os.path.join(enabled_dir, entry)):
                    return True
            except OSError:
                pass
        return False

if code == display_util.OK:
        invalid_domains = dict()
        retry_message = ""
        try:
            domain_list = display_util.separate_list_input(input_)
        except UnicodeEncodeError:
            domain_list = []
            retry_message = (
                "Internationalized domain names are not presently "
                "supported.{0}{0}Would you like to re-enter the "
                "names?{0}").format(os.linesep)

        for domain in domain_list:
            try:
                le_util.check_domain_sanity(domain)
            except errors.ConfigurationError as e:
                invalid_domains[domain] = e.message

        if len(invalid_domains):
            retry_message = (
                "One or more of the entered domain names was not valid:"
                "{0}{0}").format(os.linesep)
            for domain in invalid_domains:
                retry_message = retry_message + "{1}: {2}{0}".format(
                    os.linesep, domain, invalid_domains[domain])
            retry_message = retry_message + (
                "{0}Would you like to re-enter the names?{0}").format(
                    os.linesep)

        if retry_message:
            # We had error in input
            retry = util(interfaces.IDisplay).yesno(retry_message)