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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 update_video_status(edx_video_id, status):
 """ Update status for an existing video. Args: edx_video_id: ID of the video status: video status Raises: Raises ValVideoNotFoundError if the video cannot be retrieved. """


    try:
        video = _get_video(edx_video_id)
    except Video.DoesNotExist:
        error_message = u"Video not found when trying to update video status with edx_video_id: {0}".format(
            edx_video_id
        )
        raise ValVideoNotFoundError(error_message)

    video.status = status
    video.save()