code: function (key) {
              var modelVal = this.getModelVal();
              modelVal = this.multiple ? modelVal : [modelVal];
              return (_.indexOf(_.map(modelVal, toStr), toStr(key)) > -1);
          }
docs: Returns true or false if the option should be selected
  @memberOf Backbone.fields.SelectListView#
  @param {string} key The key of the possibleVal that is being tested
  @return {boolean}