code: function(item) {
          var itemIsId = Selectivity.isValidId(item);
          var id = itemIsId ? item : this.validateItem(item) && item.id;
  
          if (this.options.allowDuplicates || this._value.indexOf(id) === -1) {
              this._value.push(id);
  
              if (itemIsId && this.options.initSelection) {
                  this.options.initSelection(
                      [id],
                      function(data) {
                          if (this._value.indexOf(id) > -1) {
                              item = this.validateItem(data[0]);
                              this._data.push(item);
  
                              this.triggerChange({ added: item });
                          }
                      }.bind(this)
                  );
              } else {
                  if (itemIsId) {
                      item = this.getItemForId(id);
                  }
                  this._data.push(item);
  
                  this.triggerChange({ added: item });
              }
          }
  
          this.input.value = '';
          this._updateInputWidth();
      }
docs: Adds an item to the selection, if it's not selected yet.
  
  @param item The item to add. May be an item with 'id' and 'text' properties or just an ID.