code: function List(name, expiry, maxLength) {
    this.name = name;
    this.expiry = expiry;
    this.maxLength = maxLength;
    this.idGen = new IdGen('id_gen:/'+name);
  }
docs: Define a list abstraction: 1. Autoincrementing ID when pushed 2. Expiry option for removal after usage 3. Trim older values after maxLength