将月份从名称转换为数字

import datetime

def month_to_number(month_name):
    month_name = month_name.lower()
    if month_name == 'january' or month_name == 'jan':
        return 1
    elif month_name == 'february' or month_name == 'feb':
        return 2
    elif month_name == 'march' or month_name == 'mar':
        return 3
    elif month_name == 'april' or month_name == 'apr':
        return 4
    elif month_name == 'may':
        return 5
    elif month_name == 'june' or month_name == 'jun':
        return 6
    elif month_name == 'july' or month_name == 'jul':
        return 7
    elif month_name == 'august' or month_name == 'aug':
        return 8
    elif month_name == 'september' or month_name == 'sep':
        return 9
    elif month_name == 'october' or month_name == 'oct':
        return 10
    elif month_name == 'november' or month_name == 'nov':
        return 11
    elif month_name == 'december' or month_name == 'dec':
        return 12
    else:
        return None

month_name = input("请输入月份名称：")
month_number = month_to_number(month_name)
if month_number:
    print(f"{month_name}对应的数字是{month_number}。")
else:
    print("输入的月份名称无效。")