xmas market invitation in Python

gistfile1.py

# -*- coding: utf-8 -*-
#
# frwd to other interested parties at the institute
#
import datetime
import time

leave_at = datetime.datetime(2012,12,13,12,00)
while True:
    delta = leave_at - datetime.datetime.now()
    if abs(delta.seconds) < 120:
        raise SystemExit, u"Immediately leave for *xmas market Esslingen*, " +\
            u"12:14 S-Bahn UNIVERSITÄT, 13th Dec. 2012"
    elif delta.seconds > 0:
        hh = delta.seconds / 3600
        mm = (delta.seconds % 3600) / 60
        ss = delta.seconds % 60
        print("Leave for *xmas market Esslingen* in %dh %dm %ds" %
              (hh, mm, ss))
    else:
        raise ValueError, "Too late, you missed joining us!"
    time.sleep(1)