code: def get_standardized_timestamp(timestamp, ts_format):
    
    if not timestamp:
      return None
    if timestamp == 'now':
      timestamp = str(datetime.datetime.now())
    if not ts_format:
      ts_format = detect_timestamp_format(timestamp)
    try:
      if ts_format == 'unknown':
        logger.error('Unable to determine timestamp format for : %s', timestamp)
        return -1
      elif ts_format == 'epoch':
        ts = int(timestamp) * 1000
      elif ts_format == 'epoch_ms':
        ts = timestamp
      elif ts_format == 'epoch_fraction':
        ts = int(timestamp[:10]) * 1000 + int(timestamp[11:])
      elif ts_format in ('%H:%M:%S', '%H:%M:%S.%f'):
        date_today = str(datetime.date.today())
        dt_obj = datetime.datetime.strptime(date_today + ' ' + timestamp, '%Y-%m-%d ' + ts_format)
        ts = calendar.timegm(dt_obj.utctimetuple()) * 1000 + dt_obj.microsecond / 1000
      else:
        dt_obj = datetime.datetime.strptime(timestamp, ts_format)
        ts = calendar.timegm(dt_obj.utctimetuple()) * 1000 + dt_obj.microsecond / 1000
    except ValueError:
      return -1
    return str(ts)
docs: Given a timestamp string, return a time stamp in the epoch ms format. If no date is present in
    timestamp then today's date will be added as a prefix before conversion to epoch ms