code: def iso_datetime(timestamp=None):
      
      if timestamp is None:
          timestamp = time.time()
      return datetime.datetime.fromtimestamp(timestamp).isoformat(' ')[:19]
docs: Convert UNIX timestamp to ISO datetime string.
  
          @param timestamp: UNIX epoch value (default: the current time).
          @return: Timestamp formatted as "YYYY-mm-dd HH:MM:SS".