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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 get(self, request):
 """Gets the user_id for the request. Gets the ticket for the request using the get_ticket() function, and authenticates the ticket. Args: request: aiohttp Request object. Returns: The userid for the request, or None if the ticket is not authenticated. """

        ticket = await self.get_ticket(request)
        if ticket is None:
            return None

        try:
            # Returns a tuple of (user_id, token, userdata, validuntil)
            now = time.time()
            fields = self._ticket.validate(ticket, self._get_ip(request), now)

            # Check if we need to reissue a ticket
            if (self._reissue_time is not None and
                now >= (fields.valid_until - self._reissue_time)):

                # Reissue our ticket, and save it in our request.
                request[_REISSUE_KEY] = self._new_ticket(request, fields.user_id)

            return fields.user_id

        except TicketError as e:
            return None