code: def field_datetime_from_json(self, json_val):
          
          if type(json_val) == int:
              seconds = int(json_val)
              dt = datetime.fromtimestamp(seconds, utc)
          elif json_val is None:
              dt = None
          else:
              seconds, microseconds = [int(x) for x in json_val.split('.')]
              dt = datetime.fromtimestamp(seconds, utc)
              dt += timedelta(microseconds=microseconds)
          return dt
docs: Convert a UTC timestamp to a UTC datetime.