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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 async def async_connect(self):
 """Connect to the ASUS-WRT Telnet server."""

        self._reader, self._writer = await asyncio.open_connection(
            self._host, self._port)

        with (await self._io_lock):
            try:
                await asyncio.wait_for(self._reader.readuntil(b'login: '), 9)
            except asyncio.streams.IncompleteReadError:
                _LOGGER.error(
                    "Unable to read from router on %s:%s" % (
                        self._host, self._port))
                return
            except TimeoutError:
                _LOGGER.error("Host timeout.")
            self._writer.write((self._username + '\n').encode('ascii'))
            await self._reader.readuntil(b'Password: ')

            self._writer.write((self._password + '\n').encode('ascii'))

            self._prompt_string = (await self._reader.readuntil(
                b'#')).split(b'\n')[-1]
        self._connected = True