import re
from datetime import datetime, timezone, timedelta

def tz_str_to_tz(tz_str):
    m = re.match(r'(?<=UTC)[+|-]\d\d?(?=\:\d{2})',(tz_str))
    return int(m.group(0))


def to_timestamp(dt_str, tz_str):
    cday = datetime.strptime(dt_str, '%Y-%m-%d %H:%M:%S')
    cday = cday.replace(tzinfo=timezone(timedelta(hours=tz_str_to_tz(tz_str))))
    return cday.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('Pass')