import re
from datetime import datetime, timezone, timedelta

def to_timestamp(dt_str, tz_str):
    m = re.match(r'^UTC([+-]\d{1,2}):(\d{2})$', tz_str)
    tz_utc = timezone(timedelta(hours=int(m.group(1))))
    dt = datetime.strptime(dt_str, '%Y-%m-%d %H:%M:%S')
    dt = dt.replace(tzinfo=tz_utc)
    return dt.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')