How to use the adal.util.is_http_success function in adal

def discover(self):

        options = util.create_request_options(self, {'headers': {'Accept':'application/json'}})
        user_realm_url = self._get_user_realm_url()
        self._log.debug("Performing user realm discovery at: %(user_realm_url)s",
                        {"user_realm_url": user_realm_url.geturl()})

        operation = 'User Realm Discovery'
        resp = requests.get(user_realm_url.geturl(), headers=options['headers'],
                            proxies=self._call_context.get('proxies', None),
                            verify=self._call_context.get('verify_ssl', None))
        util.log_return_correlation_id(self._log, operation, resp)

        if resp.status_code == 429:
            resp.raise_for_status()  # Will raise requests.exceptions.HTTPError
        if not util.is_http_success(resp.status_code):
            return_error_string = u"{} request returned http error: {}".format(operation, 
                                                                               resp.status_code)
            error_response = ""
            if resp.text:
                return_error_string = u"{} and server response: {}".format(return_error_string, resp.text)
                try:
                    error_response = resp.json()
                except ValueError:
                    pass

            raise AdalError(return_error_string, error_response)

        else:
            self._parse_discovery_response(resp.text)

options = util.create_request_options(self, {'headers': {'Content-Type': 'application/soap+xml'}})

        try:
            operation = "Mex Get"
            resp = requests.get(self._url, headers=options['headers'],
                                verify=self._call_context.get('verify_ssl', None),
                                proxies=self._call_context.get('proxies', None))
            util.log_return_correlation_id(self._log, operation, resp)
        except Exception:
            self._log.exception(
                "%(operation)s request failed", {"operation": operation})
            raise

        if resp.status_code == 429:
            resp.raise_for_status()  # Will raise requests.exceptions.HTTPError
        if not util.is_http_success(resp.status_code):
            return_error_string = u"{} request returned http error: {}".format(operation, resp.status_code)
            error_response = ""
            if resp.text:
                return_error_string = u"{} and server response: {}".format(return_error_string, resp.text)
                try:
                    error_response = resp.json()
                except ValueError:
                    pass
            raise AdalError(return_error_string, error_response)
        else:
            try:
                self._mex_doc = resp.text
                #options = {'errorHandler':self._log.error}
                self._dom = ET.fromstring(self._mex_doc)
                self._parents = {c:p for p in self._dom.iter() for c in p}
                self._parse()

post_options = util.create_request_options(self, _REQ_OPTION)
        operation = "Get Device Code"
        try:
            resp = requests.post(device_code_url.geturl(), 
                                 data=url_encoded_code_request, 
                                 headers=post_options['headers'],
                                 verify=self._call_context.get('verify_ssl', None),
                                 proxies=self._call_context.get('proxies', None),
                                 timeout=self._call_context.get('timeout', None))
            util.log_return_correlation_id(self._log, operation, resp)
        except Exception:
            self._log.exception("%(operation)s request failed", {"operation": operation})
            raise

        if util.is_http_success(resp.status_code):
            user_code_info = self._handle_get_device_code_response(resp.text)
            user_code_info['correlation_id'] = resp.headers.get('client-request-id')
            return user_code_info
        else:
            if resp.status_code == 429:
                resp.raise_for_status()  # Will raise requests.exceptions.HTTPError
            return_error_string = _ERROR_TEMPLATE.format(operation, resp.status_code)
            error_response = ""
            if resp.text:
                return_error_string = u"{} and server response: {}".format(return_error_string,
                                                                           resp.text)
                try:
                    error_response = resp.json()
                except ValueError:
                    pass