def id_keep_strategy(pos_freq, neg_freq):
    """Determines strategy for ID records with multiple instances

    Two questions are answered:
    1. Should a single instance of the ID be kept at all?
    2. What class should a single record instance of the ID have?
    """
    if pos_freq == neg_freq:
        return None
    elif pos_freq > neg_freq:
        return 'Positive'
    elif neg_freq > pos_freq:
        return 'Negative'
    else:
        raise ValueError(f"{pos_freq} positives and {neg_freq} negatives makes no sense!")