code: function(dict, options) {
          Pair.call(this);
  
          this.encoder = new Encoder(dict, true, options);
          this.decoder = new Decoder(dict, true, options);
      }
docs: Constructs a new progressive PSON encoder and decoder pair.
  @exports PSON.ProgressivePair
  @class A progressive PSON encoder and decoder pair.
  @param {Array.<string>=} dict Initial dictionary
  @param {Object.<string,*>=} options Options
  @constructor
  @extends PSON.Pair