code: function() {
          var conversion = this.parse('');
          if (lastSetting) {
              var current = lastSetting.get();
              if (conversion.predictions.length === 0) {
                  conversion.predictions.push(current);
              }
              else {
                  // Remove current from predictions
                  var removed = false;
                  while (true) {
                      var index = conversion.predictions.indexOf(current);
                      if (index === -1) {
                          break;
                      }
                      conversion.predictions.splice(index, 1);
                      removed = true;
                  }
                  // If the current value wasn't something we would predict, leave it
                  if (removed) {
                      conversion.predictions.push(current);
                  }
              }
          }
          return conversion;
      }
docs: Promote the current value in any list of predictions, and add it if
  there are none.