Deletes a value from Set.
@method sjl.stdlib.SjlSet#delete
@param value {*}
@returns {sjl.stdlib.SjlSet}
function (value) {
            var _index = this._values.indexOf(value);
            if (_index > -1 && _index <= this._values.length) {
                this._values.splice(_index, 1);
            }
            return this;
        }