def get_product_history_diff(obj):
    """ Get diff list for the history of a given object e.g. Product, LoblawsProduct or NutritionFacts """
    history = obj.history.all()
    new_record = history.first()
    old_record = history.first().prev_record
    delta = new_record.diff_against(old_record)
    if len(delta.changes) > 0:
        return delta.changes
    return None