code: def duration(start, end=None):
      
      if not end:
          end = datetime.now()
      td = end - start
      return (td.microseconds + (td.seconds + td.days * 24 * 3600) * 1000000) \
          / 1000000.0
docs: Returns duration in seconds since supplied time.
      Note: time_delta.total_seconds() only available in python 2.7+
  
      :param start: datetime object
      :param end: Optional end datetime, None = now
      :returns: Seconds as decimal since start