'Rules for finding a duplicate:
- Look for a record with the same name, answer_list'

@staticmethod
def survey_complete_duplicate(item):

    answers = item.data.get('answer_list')
    table = item.table
    query = (table.answer_list == answers)
    try:
        duplicate = current.db(query).select(table.id, limitby=(0, 1)).first()
        if duplicate:
            item.id = duplicate.id
            item.method = item.METHOD.UPDATE
    except:
        return
