code: function getKinesisShardIdAndEventNoFromEventID(eventID) {
    if (eventID) {
      const sepPos = eventID.indexOf(':');
      return sepPos !== -1 ?
        [eventID.substring(0, sepPos), eventID.substring(sepPos + 1),] : ['', ''];
    }
    return ['', ''];
  }
docs: Extracts the shard id and event number from the given Kinesis eventID.
  @param {string} eventID - an eventID from an AWS Kinesis stream event record.
  @return {[string,string]} an array containing: the shard id (if any) or an empty string; and the event number (if any)
  or an empty string