def add_months(sourcedate, months=0):
"""
获取指定月份几个月之后或之前的月份及日期
:param source_date: 起始日期
:param months: 月份跨度
:return: 返回起始日期source_date与months相加之后的日期，格式为datetime.date
"""
month = sourcedate.month - 1 + months
print("month:",month)
print("sourcedate.month:",sourcedate.month+months)
year = sourcedate.year + month // 12
month = month % 12 + 1
day = min(sourcedate.day, calendar.monthrange(year,month)[1])
return datetime.date(year, month, day)