import re
from datetime import datetime, timezone, timedelta

def to_timestamp(dt_str, tz_str):
    zone=re.split(r'UTC([+\-])(\d+):\d+',tz_str)
    zonehour=int(zone[2])
    if zone[1]=='-':
        zonehour=0-int(zone[2])
    dt= datetime.strptime(dt_str, '%Y-%m-%d %H:%M:%S')
    tt= dt.replace(tzinfo=timezone(timedelta(hours=zonehour)))
    return tt.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')