docs: def format_json_date(value):
      """
      Formats a datetime as ISO8601 in UTC with millisecond precision, e.g. "2014-10-03T09:41:12.790Z"
      """
      if not value:
          return None
  
      # %f will include 6 microsecond digits
      micro_precision = value.astimezone(pytz.UTC).strftime(JSON_DATETIME_FORMAT)
  
      # only keep the milliseconds portion of the second fraction
      return micro_precision[:-4] + 'Z'