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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:
 def pin_channel(current):
 """ Pin a channel to top of channel list .. code-block:: python # request: { 'view':'_zops_pin_channel, 'channel_key': key, } # response: { 'status': 'OK', 'code': 200 } """

    try:
        Subscriber(current).objects.filter(user_id=current.user_id,
                                           channel_id=current.input['channel_key']).update(
            pinned=True)
        current.output = {'status': 'OK', 'code': 200}
    except ObjectDoesNotExist:
        raise HTTPError(404, "")