def getTopKSimilarUser(user, records, numK = 200):
    """
    Args:
        user: id of a user
        records: [(user_sim, similarity, number of common ratings)]
        numK: number of similar users we want to keep track of
    Returns:
        (user, [(user_sim, similarity, number of common ratings)])
    """
    llist = sorted(records, key=lambda x: x[1], reverse=True)
    llist = [x for x in llist if x[2] > 9]# filter out those whose cnt is small
    return (user, llist[:numK])