Parse a datetime with a timezone in python, 2.4 compatible

datetz.py

#!/usr/bin/env python

import time, calendar, datetime

input = '2011-05-26T16:02:59.199400+00:00'

def dttz(input): 
   if '+' in input: 
      return input.split('+', 1)
   else: return input, None

def timezone(tz): 
   sign, offset = tz[0], tz[1:]
   hours, minutes = tuple([int(n) for n in offset.split(':')])
   minutes += hours * 60
   if sign == '-': 
      minutes = -minutes

   class TimeZone(datetime.tzinfo): 
      def utcoffset(self, dt): 
         return datetime.timedelta(minutes=minutes)

      def dst(self, dt): 
         return datetime.timedelta(0)

   return TimeZone()

dt, tz = dttz(input)
tz = timezone(tz)
if '.' in dt: 
   dt = dt.split('.', 1)[0]
then = time.strptime(dt, '%Y-%m-%dT%H:%M:%S')
then = datetime.datetime.utcfromtimestamp(calendar.timegm(then))
then.replace(tzinfo=tz)
now = datetime.datetime.utcnow()
td = (now - then)
inner = (td.seconds + td.days * 24 * 3600)
seconds = (td.microseconds + inner * 10**6) / 10**6
minutes = float(seconds) / 60
print minutes < 5