def add_safe(self, name, url, author_id):
		"""Try to add an emote. Returns a string that should be sent to the user."""
		if not re.fullmatch(r'\w{2,32}', name, re.ASCII):
			return _(
				'{name} is not a valid emote name; use 2–32 English letters, numbers and underscores.'
			).format(name=discord.utils.escape_mentions(name))
		try:
			emote = await self.add_from_url(name, url, author_id)
		except discord.HTTPException as ex:
			return (
				_('An error occurred while creating the emote:\n')
				+ utils.format_http_exception(ex))
		except ValueError:
			return _('Error: Invalid URL.')
		except aiohttp.ServerDisconnectedError:
			return _('Error: The connection was closed early by the remote host.')
		except aiohttp.ClientResponseError as exc:
			raise errors.HTTPException(exc.status)
		else:
			return _('Emote {emote} successfully created.').format(emote=emote) 

def test_single_proxy(self, proxy):
        """
        text one proxy, if valid, put them to usable_proxies.
        """
        try:
            async with aiohttp.ClientSession() as session:
                try:
                    if isinstance(proxy, bytes):
                        proxy = proxy.decode('utf-8')
                    real_proxy = 'http://' + proxy
                    print('Testing', proxy)
                    async with session.get(self.test_api, proxy=real_proxy, timeout=get_proxy_timeout) as response:
                        if response.status == 200:
                            self._conn.put(proxy)
                            print('Valid proxy', proxy)
                except (ProxyConnectionError, TimeoutError, ValueError):
                    print('Invalid proxy', proxy)
        except (ServerDisconnectedError, ClientResponseError,ClientConnectorError) as s:
            print(s)
            pass 

def fetch(self):
        while True:

            try:
                hdrlen = constants.STREAM_HEADER_SIZE_BYTES
                header = yield from self._response.content.readexactly(hdrlen)

                _, length = struct.unpack(">BxxxL", header)
                if not length:
                    continue

                data = yield from self._response.content.readexactly(length)

            except (
                aiohttp.ClientConnectionError,
                aiohttp.ServerDisconnectedError,
                asyncio.IncompleteReadError,
            ):
                break
            return data 

def _get(self, url, data=None, headers=None, method='GET'):
        page = ''
        try:
            timeout = aiohttp.ClientTimeout(total=self._timeout)
            async with self._sem_provider, self._session.request(
                method, url, data=data, headers=headers, timeout=timeout
            ) as resp:
                page = await resp.text()
                if resp.status != 200:
                    log.debug(
                        'url: %s\nheaders: %s\ncookies: %s\npage:\n%s'
                        % (url, resp.headers, resp.cookies, page)
                    )
                    raise BadStatusError('Status: %s' % resp.status)
        except (
            UnicodeDecodeError,
            BadStatusError,
            asyncio.TimeoutError,
            aiohttp.ClientOSError,
            aiohttp.ClientResponseError,
            aiohttp.ServerDisconnectedError,
        ) as e:
            page = ''
            log.debug('%s is failed. Error: %r;' % (url, e))
        return page 

def fetch(self, url):
        """Fetch request."""
        error_msg = None
        try:
            async with aiohttp.ClientSession() as session:
                body = await self.fetch_with_session(session, url)
        except asyncio.TimeoutError:
            error_msg = 'Request timed out'
            raise ClashRoyaleAPIError(message=error_msg)
        except aiohttp.ServerDisconnectedError as err:
            error_msg = 'Server disconnected error: {}'.format(err)
            raise ClashRoyaleAPIError(message=error_msg)
        except (aiohttp.ClientError, ValueError) as err:
            error_msg = 'Request connection error: {}'.format(err)
            raise ClashRoyaleAPIError(message=error_msg)
        except json.JSONDecodeError:
            error_msg = "Non JSON returned"
            raise ClashRoyaleAPIError(message=error_msg)
        else:
            return body
        finally:
            if error_msg is not None:
                raise ClashRoyaleAPIError(message=error_msg) 

def target_fetch(url, headers, timeout=15):
    """
    :param url: target url
    :return: text
    """
    with async_timeout.timeout(timeout):
        try:
            async with aiohttp.ClientSession() as client:
                async with client.get(url, headers=headers) as response:
                    assert response.status == 200
                    LOGGER.info('Task url: {}'.format(response.url))
                    try:
                        text = await response.text()
                    except:
                        try:
                            text = await response.read()
                        except aiohttp.ServerDisconnectedError as e:
                            LOGGER.exception(e)
                            text = None
                    return text
        except Exception as e:
            LOGGER.exception(str(e))
            return None 

def _arequest(self, url, **params):
        method = params.get('method', 'GET')
        json_data = params.get('json', {})
        timeout = params.pop('timeout', None) or self.timeout
        try:
            async with self.session.request(
                method, url, timeout=timeout, headers=self.headers, params=params, data=json_data
            ) as resp:
                return self._raise_for_status(resp, await resp.text())
        except asyncio.TimeoutError:
            raise NotResponding
        except aiohttp.ServerDisconnectedError:
            raise NetworkError 

def _arequest(self, url, **params):
        timeout = params.pop('timeout', None) or self.timeout
        try:
            async with self.session.get(url, timeout=timeout, headers=self.headers, params=params) as resp:
                return self._raise_for_status(resp, await resp.text())
        except asyncio.TimeoutError:
            raise NotResponding
        except aiohttp.ServerDisconnectedError:
            raise NetworkError 

def fail_with_disconnected_error():
    raise aiohttp.ServerDisconnectedError("Darn it, can't connect") 

def handle_exception():
    """
    Context manager translating network related exceptions
    to custom :mod:`~galaxy.api.errors`.
    """
    try:
        yield
    except asyncio.TimeoutError:
        raise BackendTimeout()
    except aiohttp.ServerDisconnectedError:
        raise BackendNotAvailable()
    except aiohttp.ClientConnectionError:
        raise NetworkError()
    except aiohttp.ContentTypeError:
        raise UnknownBackendResponse()
    except aiohttp.ClientResponseError as error:
        if error.status == HTTPStatus.UNAUTHORIZED:
            raise AuthenticationRequired()
        if error.status == HTTPStatus.FORBIDDEN:
            raise AccessDenied()
        if error.status == HTTPStatus.SERVICE_UNAVAILABLE:
            raise BackendNotAvailable()
        if error.status == HTTPStatus.TOO_MANY_REQUESTS:
            raise TooManyRequests()
        if error.status >= 500:
            raise BackendError()
        if error.status >= 400:
            logging.warning(
                "Got status %d while performing %s request for %s",
                error.status, error.request_info.method, str(error.request_info.url)
            )
            raise UnknownError()
    except aiohttp.ClientError:
        logging.exception("Caught exception while performing request")
        raise UnknownError() 

def __anext__(self):
        while True:
            try:
                data = yield from self._response.content.readline()
                if not data:
                    break
            except (aiohttp.ClientConnectionError, aiohttp.ServerDisconnectedError):
                break
            return self._transform(json.loads(data.decode("utf8")))

        raise StopAsyncIteration 

def run(self, **params):
        if self.response:
            warnings.warn("already running", RuntimeWarning, stackelevel=2)
            return
        forced_params = {"follow": True}
        default_params = {"stdout": True, "stderr": True}
        params = ChainMap(forced_params, params, default_params)
        try:
            self.response = await self.docker._query(
                "containers/{self.container._id}/logs".format(self=self), params=params
            )
            while True:
                msg = await self.response.content.readline()
                if not msg:
                    break
                await self.channel.publish(msg)
        except (aiohttp.ClientConnectionError, aiohttp.ServerDisconnectedError):
            pass
        finally:
            # signal termination to subscribers
            await self.channel.publish(None)
            try:
                await self.response.release()
            except Exception:
                pass
            self.response = None 

def test_body_match(aresponses):
    aresponses.add("foo.com", "/", "get", aresponses.Response(text="hi"), body_pattern=re.compile(r".*?apple.*"))

    url = "http://foo.com"
    async with aiohttp.ClientSession() as session:
        try:
            async with session.get(url, data={"fruit": "pineapple"}) as response:
                text = await response.text()
                assert text == "hi"
        except ServerDisconnectedError:
            pass

    aresponses.assert_plan_strictly_followed() 

def test_failure_no_match(aresponses):
    async with aiohttp.ClientSession() as session:
        try:
            async with session.get("http://foo.com") as response:
                await response.text()
        except ServerDisconnectedError:
            pass
    with pytest.raises(NoRouteFoundError):
        aresponses.assert_all_requests_matched()

    with pytest.raises(NoRouteFoundError):
        aresponses.assert_plan_strictly_followed() 

def fetch_multi(self, urls):
        """Perform parallel fetch"""
        results = []
        error_msg = None
        try:
            async with aiohttp.ClientSession() as session:
                for url in urls:
                    await asyncio.sleep(0)
                    body = await self.fetch_with_session(session, url)
                    results.append(body)
        except asyncio.TimeoutError:
            error_msg = 'Request timed out'
            raise ClashRoyaleAPIError(message=error_msg)
        except aiohttp.ServerDisconnectedError as err:
            error_msg = 'Server disconnected error: {}'.format(err)
            raise ClashRoyaleAPIError(message=error_msg)
        except (aiohttp.ClientError, ValueError) as err:
            error_msg = 'Request connection error: {}'.format(err)
            raise ClashRoyaleAPIError(message=error_msg)
        except json.JSONDecodeError:
            error_msg = "Non JSON returned"
            raise ClashRoyaleAPIError(message=error_msg)
        else:
            return results
        finally:
            if error_msg is not None:
                raise ClashRoyaleAPIError(message=error_msg) 

def test_disconnect(self, mock_book, mock_connect):
        mock_connect.return_value.aenter.receive_str = CoroutineMock()
        mock_connect.return_value.aenter.send_json = CoroutineMock()
        mock_book.return_value = {'bids': [], 'asks': [], 'sequence': 1}

        messages_expected = [
            json.dumps({
              "type": "done",
              "side": "sell",
              "order_id": "4eef1226-4b38-422c-a5b1-56def7107f9a",
              "reason": "canceled",
              "product_id": "ETH-USD",
              "price": "2601.76000000",
              "remaining_size": "3.09000000",
              "sequence": 2,
              "time": "2017-06-25T11:23:14.775000Z"
            }),
            aiohttp.ServerDisconnectedError('error'),
            json.dumps({
              "type": "done",
              "side": "sell",
              "order_id": "4eef1226-4b38-422c-a5b1-56def7107f9a",
              "reason": "canceled",
              "product_id": "ETH-USD",
              "price": "2601.76000000",
              "remaining_size": "3.09000000",
              "sequence": 2,
              "time": "2017-06-25T11:23:14.775000Z"
            })
        ]
        mock_connect.return_value.aenter.receive_str.side_effect = \
            messages_expected
        async with gdax.orderbook.OrderBook() as orderbook:
            message = await orderbook.handle_message()
            assert message == json.loads(messages_expected[0])

            message = await orderbook.handle_message()
            assert message is None

            message = await orderbook.handle_message()
            assert message == json.loads(messages_expected[2]) 

def handle_exception():
    """
    Context manager translating network related exceptions
    to custom :mod:`~galaxy.api.errors`.
    """
    try:
        yield
    except asyncio.TimeoutError:
        raise BackendTimeout()
    except aiohttp.ServerDisconnectedError:
        raise BackendNotAvailable()
    except aiohttp.ClientConnectionError:
        raise NetworkError()
    except aiohttp.ContentTypeError as error:
        raise UnknownBackendResponse(error.message)
    except aiohttp.ClientResponseError as error:
        if error.status == HTTPStatus.UNAUTHORIZED:
            raise AuthenticationRequired(error.message)
        if error.status == HTTPStatus.FORBIDDEN:
            raise AccessDenied(error.message)
        if error.status == HTTPStatus.SERVICE_UNAVAILABLE:
            raise BackendNotAvailable(error.message)
        if error.status == HTTPStatus.TOO_MANY_REQUESTS:
            raise TooManyRequests(error.message)
        if error.status >= 500:
            raise BackendError(error.message)
        if error.status >= 400:
            logger.warning(
                "Got status %d while performing %s request for %s",
                error.status, error.request_info.method, str(error.request_info.url)
            )
            raise UnknownError(error.message)
    except aiohttp.ClientError as e:
        logger.exception("Caught exception while performing request")
        raise UnknownError(repr(e)) 

def request(self, method, endpoint, body, headers=None, query=None):
        if headers is None:
            headers = {}
        if query is None:
            query = {}

        if body is not None:
            if isinstance(body, str):
                headers["Content-Type"] = "text/plain"
            else:
                body = json.dumps(body)
                headers["Content-Type"] = "application/json"

        if self.debug:
            print(f"{method} {endpoint}: {body}")
        data = None
        async with aiohttp.ClientSession() as session:
            for _ in range(MAX_TRIES):
                try:
                    async with session.request(method, f"{self.base}{endpoint}", data=body, headers=headers,
                                               params=query) as resp:
                        log.info(f"Dicecloud returned {resp.status} ({endpoint})")
                        if resp.status == 200:
                            data = await resp.json(encoding='utf-8')
                            break
                        elif resp.status == 429:
                            timeout = await resp.json(encoding='utf-8')
                            log.warning(f"Dicecloud ratelimit hit ({endpoint}) - resets in {timeout}ms")
                            await asyncio.sleep(timeout['timeToReset'] / 1000)  # rate-limited, wait and try again
                        elif 400 <= resp.status < 600:
                            if resp.status == 403:
                                raise Forbidden(resp.reason)
                            elif resp.status == 404:
                                raise NotFound(resp.reason)
                            else:
                                raise HTTPException(resp.status, resp.reason)
                        else:
                            log.warning(f"Unknown response from Dicecloud: {resp.status}")
                except aiohttp.ServerDisconnectedError:
                    raise HTTPException(None, "Server disconnected")
        if not data:  # we did 10 loops and always got either 200 or 429 but we have no data, so we must have 429ed
            raise Timeout(f"Dicecloud failed to respond after {MAX_TRIES} tries. Please try again.")

        return data 

def _send(self, payload, processor):
        """Send a payload to be converted to JSON.

        Handles temporary connection issues.  Daemon reponse errors
        are raise through DaemonError.
        """
        def log_error(error):
            nonlocal last_error_log, retry
            now = time.time()
            if now - last_error_log > 60:
                last_error_log = now
                self.logger.error(f'{error}  Retrying occasionally...')
            if retry == self.max_retry and self.failover():
                retry = 0

        on_good_message = None
        last_error_log = 0
        data = json.dumps(payload)
        retry = self.init_retry
        while True:
            try:
                result = await self._send_data(data)
                result = processor(result)
                if on_good_message:
                    self.logger.info(on_good_message)
                return result
            except asyncio.TimeoutError:
                log_error('timeout error.')
            except aiohttp.ServerDisconnectedError:
                log_error('disconnected.')
                on_good_message = 'connection restored'
            except aiohttp.ClientConnectionError:
                log_error('connection problem - is your daemon running?')
                on_good_message = 'connection restored'
            except aiohttp.ClientError as e:
                log_error(f'daemon error: {e}')
                on_good_message = 'running normally'
            except WarmingUpError:
                log_error('starting up checking blocks.')
                on_good_message = 'running normally'
            except WorkQueueFullError:
                log_error('work queue full.')
                on_good_message = 'running normally'

            await asyncio.sleep(retry)
            retry = max(min(self.max_retry, retry * 2), self.init_retry) 

def read(self, url, *args, use_proxy=False, **kwargs) -> FeedResponse:
        headers = content = None
        try:
            if use_proxy:
                headers, content, url, status = await self._read_by_proxy(url, *args, **kwargs)
            else:
                headers, content, url, status = await self._read(url, *args, **kwargs)
        except (socket.gaierror, aiodns.error.DNSError):
            status = FeedResponseStatus.DNS_ERROR.value
        except (socket.timeout, TimeoutError, aiohttp.ServerTimeoutError,
                asyncio.TimeoutError, concurrent.futures.TimeoutError):
            status = FeedResponseStatus.CONNECTION_TIMEOUT.value
        except (ssl.SSLError, ssl.CertificateError,
                aiohttp.ServerFingerprintMismatch,
                aiohttp.ClientSSLError,
                aiohttp.ClientConnectorSSLError,
                aiohttp.ClientConnectorCertificateError):
            status = FeedResponseStatus.SSL_ERROR.value
        except (aiohttp.ClientProxyConnectionError,
                aiohttp.ClientHttpProxyError):
            status = FeedResponseStatus.PROXY_ERROR.value
        except (ConnectionError,
                aiohttp.ServerDisconnectedError,
                aiohttp.ServerConnectionError,
                aiohttp.ClientConnectionError,
                aiohttp.ClientConnectorError):
            status = FeedResponseStatus.CONNECTION_RESET.value
        except (aiohttp.WSServerHandshakeError, aiohttp.ClientOSError):
            status = FeedResponseStatus.CONNECTION_ERROR.value
        except aiohttp.ClientPayloadError:
            status = FeedResponseStatus.CHUNKED_ENCODING_ERROR.value
        except UnicodeDecodeError:
            status = FeedResponseStatus.CONTENT_DECODING_ERROR.value
        except FeedReaderError as ex:
            status = ex.status
            LOG.warning(type(ex).__name__ + " url=%s %s", url, ex)
        except (aiohttp.ClientResponseError, aiohttp.ContentTypeError) as ex:
            status = ex.status
        except (aiohttp.ClientError, aiohttp.InvalidURL):
            status = FeedResponseStatus.UNKNOWN_ERROR.value
        builder = FeedResponseBuilder(use_proxy=use_proxy)
        builder.url(url)
        builder.status(status)
        builder.content(content)
        builder.headers(headers)
        return builder.build() 

def _send(self, payload, processor):
        """Send a payload to be converted to JSON.

        Handles temporary connection issues.  Daemon response errors
        are raise through DaemonError.
        """

        def log_error(error):
            nonlocal last_error_log, retry
            now = time.time()
            if now - last_error_log > 60:
                last_error_log = now
                self.logger.error(f'{error}  Retrying occasionally...')
            if retry == self.max_retry and self.failover():
                retry = 0

        on_good_message = None
        last_error_log = 0
        data = json.dumps(payload)
        retry = self.init_retry
        methods = tuple(
            [payload['method']] if isinstance(payload, dict) else [request['method'] for request in payload]
        )
        while True:
            try:
                for method in methods:
                    self.lbrycrd_pending_count_metric.labels(method=method).inc()
                result = await self._send_data(data)
                result = processor(result)
                if on_good_message:
                    self.logger.info(on_good_message)
                return result
            except asyncio.TimeoutError:
                log_error('timeout error.')
            except aiohttp.ServerDisconnectedError:
                log_error('disconnected.')
                on_good_message = 'connection restored'
            except aiohttp.ClientConnectionError:
                log_error('connection problem - is your daemon running?')
                on_good_message = 'connection restored'
            except aiohttp.ClientError as e:
                log_error(f'daemon error: {e}')
                on_good_message = 'running normally'
            except WarmingUpError:
                log_error('starting up checking blocks.')
                on_good_message = 'running normally'
            except WorkQueueFullError:
                log_error('work queue full.')
                on_good_message = 'running normally'
            finally:
                for method in methods:
                    self.lbrycrd_pending_count_metric.labels(method=method).dec()
            await asyncio.sleep(retry)
            retry = max(min(self.max_retry, retry * 2), self.init_retry) 

def check(self, real_ext_ip):
        # TODO: need refactoring
        try:
            self.ip = await self._resolver.resolve(self.host)
        except ResolveError:
            return

        if self.scheme == 'SMTP':
            self.is_working = True
            self.available[self.scheme].append(self)
            self.ev[self.scheme].set()
            return

        page = False
        headers, rv = get_headers(rv=True)
        connector = aiohttp.TCPConnector(
            loop=self._loop, ssl=self.verify_ssl, force_close=True
        )
        try:
            timeout = aiohttp.ClientTimeout(total=self.timeout)
            async with aiohttp.ClientSession(
                connector=connector, timeout=timeout, loop=self._loop
            ) as session, session.get(
                url=self.url, headers=headers, allow_redirects=False
            ) as resp:
                page = await resp.text()
        except (
            asyncio.TimeoutError,
            aiohttp.ClientOSError,
            aiohttp.ClientResponseError,
            aiohttp.ServerDisconnectedError,
        ) as e:
            log.debug('%s is failed. Error: %r;' % (self, e))
            return

        page = page.lower()

        if resp.status == 200 and real_ext_ip in page and rv in page:
            self.marks['via'] = page.count('via')
            self.marks['proxy'] = page.count('proxy')
            self.is_working = True
            self.available[self.scheme].append(self)
            self.ev[self.scheme].set()
            log.debug('%s is verified' % self)
        else:
            log.debug(
                (
                    '{j} is failed. HTTP status code: {code}; '
                    'Real IP on page: {ip}; Version: {word}; '
                    'Response: {page}'
                ).format(
                    j=self,
                    code=resp.status,
                    page=page,
                    ip=(real_ext_ip in page),
                    word=(rv in page),
                )
            ) 

def handle_message(self):
        try:
            message = await self._recv()
        except aiohttp.ServerDisconnectedError as exc:
            logging.error(
                f'Error: Exception: f{exc}. Re-initializing websocket.')
            await self.__aexit__(None, None, None)
            await self.__aenter__()
            return

        msg_type = message['type']

        if msg_type == 'error':
            raise OrderBookError(f'Error: {message["message"]}')

        if msg_type == 'subscriptions':
            return  # must filter out here because the subscriptions message does not have a product_id key

        product_id = message['product_id']
        assert self._sequences[product_id] is not None
        sequence = message['sequence']

        if sequence <= self._sequences[product_id]:
            # ignore older messages (e.g. before order book initialization
            # from getProductOrderBook)
            return message
        elif sequence > self._sequences[product_id] + 1:
            logging.error(
                'Error: messages missing ({} - {}). Re-initializing websocket.'
                .format(sequence, self._sequences[product_id]))
            await self.__aexit__(None, None, None)
            await self.__aenter__()
            return

        if msg_type == 'open':
            self.add(product_id, message)
        elif msg_type == 'done' and 'price' in message:
            self.remove(product_id, message)
        elif msg_type == 'match':
            self.match(product_id, message)
        elif msg_type == 'change':
            self.change(product_id, message)
        elif msg_type == 'heartbeat':
            pass
        elif msg_type == 'received':
            pass
        elif msg_type == 'done':
            pass
        else:
            raise OrderBookError(f'unknown message type {msg_type}')

        self._sequences[product_id] = sequence
        return message 

def fetch(self, method, url, params=None, headers=None, data=None):
        """Make an HTTP request.

        Automatically uses configured HTTP proxy, and adds Google authorization
        header and cookies.

        Failures will be retried MAX_RETRIES times before raising NetworkError.

        Args:
            method (str): Request method.
            url (str): Request URL.
            params (dict): (optional) Request query string parameters.
            headers (dict): (optional) Request headers.
            data: (str): (optional) Request body data.

        Returns:
            FetchResponse: Response data.

        Raises:
            NetworkError: If the request fails.
        """
        logger.debug('Sending request %s %s:\n%r', method, url, data)
        for retry_num in range(MAX_RETRIES):
            try:
                async with self.fetch_raw(method, url, params=params,
                                          headers=headers, data=data) as res:
                    async with async_timeout.timeout(REQUEST_TIMEOUT):
                        body = await res.read()
                logger.debug('Received response %d %s:\n%r',
                             res.status, res.reason, body)
            except asyncio.TimeoutError:
                error_msg = 'Request timed out'
            except aiohttp.ServerDisconnectedError as err:
                error_msg = 'Server disconnected error: {}'.format(err)
            except (aiohttp.ClientError, ValueError) as err:
                error_msg = 'Request connection error: {}'.format(err)
            else:
                break
            logger.info('Request attempt %d failed: %s', retry_num, error_msg)
        else:
            logger.info('Request failed after %d attempts', MAX_RETRIES)
            raise exceptions.NetworkError(error_msg)

        if res.status != 200:
            logger.info('Request returned unexpected status: %d %s',
                        res.status, res.reason)
            raise exceptions.NetworkError(
                'Request return unexpected status: {}: {}'
                .format(res.status, res.reason)
            )

        return FetchResponse(res.status, body) 

def _longpoll_request(self):
        """Open a long-polling request and receive arrays.

        This method uses keep-alive to make re-opening the request faster, but
        the remote server will set the "Connection: close" header once an hour.

        Raises hangups.NetworkError or ChannelSessionError.
        """
        params = {
            'VER': 8,  # channel protocol version
            'gsessionid': self._gsessionid_param,
            'RID': 'rpc',  # request identifier
            't': 1,  # trial
            'SID': self._sid_param,  # session ID
            'CI': 0,  # 0 if streaming/chunked requests should be used
            'ctype': 'hangouts',  # client type
            'TYPE': 'xmlhttp',  # type of request
        }
        logger.info('Opening new long-polling request')
        try:
            async with self._session.fetch_raw('GET', CHANNEL_URL,
                                               params=params) as res:

                if res.status != 200:
                    if res.status == 400 and res.reason == 'Unknown SID':
                        raise ChannelSessionError('SID became invalid')
                    raise exceptions.NetworkError(
                        'Request return unexpected status: {}: {}'.format(
                            res.status, res.reason))

                while True:
                    async with async_timeout.timeout(PUSH_TIMEOUT):
                        chunk = await res.content.read(MAX_READ_BYTES)
                    if not chunk:
                        break

                    await self._on_push_data(chunk)

        except asyncio.TimeoutError:
            raise exceptions.NetworkError('Request timed out')
        except aiohttp.ServerDisconnectedError as err:
            raise exceptions.NetworkError(
                'Server disconnected error: %s' % err)
        except aiohttp.ClientPayloadError:
            raise ChannelSessionError('SID is about to expire')
        except aiohttp.ClientError as err:
            raise exceptions.NetworkError('Request connection error: %s' % err)