code: function Underverse(size, cursor) {
    if (!(this instanceof Underverse)) return new Underverse(size);
  
    this.size = size || 10000;            // The size of the backlog.
    this.ring = new Array(this.size);     // The ring we are going to abuse.
    this.position = isNaN(+cursor)        // Current position of the cursor.
      ? 'inactive'
      : +cursor;
  }
docs: Underverse is backlog state manager. The items in the backlog can have
  various of states:
  
  - undefined: This items is not fetched or received yet.
  - 0: The item is currently beeing fetched.
  - 1: The item is fetched
  
  The underverse tells you when your id's are out of sync and if there are
  messages to be fetched. It assumes that your ids are numbers and are issued
  in order.
  
  @constructor
  @param {Number} size The size of the backlog
  @param {Number} cursor Initial start position
  @api public