# update: 2022-6-17


def get_last(data_list, amount):
    """获取尾部元素"""
    return data_list[-amount:]


def cut_last(data_list, amount):
    """去掉尾部元素"""
    return data_list[:-amount]


def get_head(data_list, amount):
    """获取头部元素"""
    return data_list[:amount]


def cut_head(data_list, amount):
    """去掉头部元素"""
    return data_list[amount:]


def reverse(string_or_list):
    """倒序"""
    if type(string_or_list) not in [str, list]:
        return ''
    return string_or_list[::-1]