'Try to refresh a show
:param indexer_id: The unique id of the show to refresh
:return: A tuple containing:
- an error message if the show could not be refreshed, ``None`` otherwise
- the show object that was refreshed, if it exists, ``None`` otherwise'

@staticmethod
def refresh(indexer_id):

    (error, show) = Show._validate_indexer_id(indexer_id)
    if (error is not None):
        return (error, show)
    try:
        sickbeard.showQueueScheduler.action.refresh_show(show)
    except CantRefreshShowException as exception:
        return (ex(exception), show)
    return (None, show)
