import re
from datetime import datetime, timezone, timedelta

def to_timestamp(dt_str, tz_str):
    #把用户输入的字符串转换成时间    
    localtime = datetime.strptime(dt_str, '%Y-%m-%d %H:%M:%S')
    #通过字符串获取时区    
    tznum = re.match(r'^(UTC)([\+\-](\d)+)(:00)$',tz_str)
    tz = timezone(timedelta(hours=int(tznum.group(2))))
    # 把用户输入的时间转成标准时区时间    
    resulttime = localtime.replace(tzinfo=tz)
    return resulttime.timestamp()


t1 = to_timestamp('2015-6-1 08:10:30', 'UTC+7:00')
assert t1 == 1433121030.0, t1

t2 = to_timestamp('2015-5-31 16:10:30', 'UTC-09:00')
assert t2 == 1433121030.0, t2

print('ok')

廖老师的习题import模块提示了解决思路，代码测试OK