code: def time2isoz(t=None):
      
      if t is None:
          dt = datetime.datetime.utcnow()
      else:
          dt = datetime.datetime.utcfromtimestamp(t)
      return "%04d-%02d-%02d %02d:%02d:%02dZ" % (
          dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second)
docs: Return a string representing time in seconds since epoch, t.
  
      If the function is called without an argument, it will use the current
      time.
  
      The format of the returned string is like "YYYY-MM-DD hh:mm:ssZ",
      representing Universal Time (UTC, aka GMT).  An example of this format is:
  
      1994-11-24 08:49:37Z