def next_token(mention):
    """ Compute the token following a mention.

    Args:
        mention (Mention): A mention.

    Returns:
        The tuple ('next', TOKEN), where TOKEN is the (lowercased) token
        following the mention. If no such token exists, set TOKEN to 'NONE'.
    """
    next_t = mention.get_context(1)

    if next_t:
        return "next", next_t[0].lower()
    else:
        return "next", "NONE"