from datetime import datetime, timezone, timedelta
import re

def to_stamp(dt_str, tz_str):
    dt = datetime.strptime(dt_str, '%Y-%m-%d %H:%M:%S')
    m = re.match(r'^UTC(\+|\-)0?([0-9])\:00$', tz_str)
    tz = int(m.group(2)) if m.group(1) == '+' else -int(m.group(2))
    dt = dt.replace(tzinfo = timezone(timedelta(hours = tz)))
    return dt.timestamp()

a = to_stamp('2015-6-1 08:10:30', 'UTC+7:00')
b = to_stamp('2015-5-31 16:10:30', 'UTC-09:00')
print(a, b)