code: function getKinesisShardIdFromEventID(eventID) {
    if (eventID) {
      const sepPos = eventID.indexOf(':');
      return sepPos !== -1 ? eventID.substring(0, sepPos) : '';
    }
    return '';
  }
docs: Extracts the shard id from the given Kinesis eventID.
  @param {string} eventID - an eventID from an AWS Kinesis stream event record.
  @return {string|undefined} the shard id (if any) or an empty string