0302-凭证冲销

import pandas as pd
from datetime import datetime
from dateutil.relativedelta import relativedelta

def get_previous_month(calendar_str: str) -> str:
    """
    根据YYYYMM格式的年月获取上个月的YYYYMM格式
    
    Args:
        calendar_str: YYYYMM格式的年月字符串
        
    Returns:
        YYYYMM格式的上个月年月字符串
    """
    # 解析字符串为日期对象（设置为该月的第一天）
    current_date = datetime.strptime(calendar_str, "%Y%m")

    # 计算上个月
    previous_date = current_date - relativedelta(months=1)

    # 格式化为YYYYMM
    return previous_date.strftime("%Y%m")

def main():
    # 从Pipeline.params获取calendar参数
    calendar_str = Pipeline.params.get("calendar")

    if not calendar_str:
        raise ValueError("未找到calendar参数")

    # 获取上个月
    previous_month = get_previous_month(calendar_str)

    return previous_month

# 调用主函数
result = main()
result