code: def force_utc(time, name='field', precision=6):
      
      if not isinstance(time, datetime.datetime):
          raise CloudValueError("%s should be of type datetime" % (name,))
      clip = 6 - precision
      timestring = time.isoformat()
      if clip:
          timestring = timestring[:-clip]
      return timestring + "Z"
docs: Appending 'Z' to isoformatted time - explicit timezone is required for most APIs