code: def parse_duration(duration, timestamp=None):
          
          assert isinstance(duration, basestring)
          assert timestamp is None or isinstance(timestamp, int)
  
          timedelta = duration_parser(duration)
          if timestamp is None:
              data = datetime.utcnow() + timedelta
          else:
              data = datetime.utcfromtimestamp(timestamp) + timedelta
          return calendar.timegm(data.utctimetuple())
docs: Interprets a ISO8601 duration value relative to a given timestamp.
  
          :param duration: The duration, as a string.
          :type: string
  
          :param timestamp: The unix timestamp we should apply the duration to.
                            Optional, default to the current time.
          :type: string
  
          :return: The new timestamp, after the duration is applied.
          :rtype: int