code: function() {
              var selector = this.options.valueSelector;
              if (_.isFunction(selector)) {
                  this.value = selector(this);
              } else if (_.isString(selector)) {
                  this.value = this[selector]();
              } else {
                  this.value = selector;
              }
              return this.value;
          }
docs: /*
  Return final value