Advances (or reverses) the date the specified number of days.
@param {Number} n The number object to operate on.
@param {Date} date The date to change.
@return {Date} The modified date.
function secondsFrom (n, date) {
                    if(typeof date === 'number') date = new Date(date);
                    if(!(date instanceof Date))  date = new Date();

                    date.setSeconds(date.getSeconds() + n);
                    return date;
                }