{buffer.set(birthday, "1973-12-12T10:10:00")}

Birthday: {buffer.get(birthday)}
Day of week born: {locale.weekdayname(datetime.getdayofweek($birthday))}
Day of month born: {datetime.getday($birthday)} 
Day of year born: {datetime.getdayofyear($birthday)}
Birthday month had {datetime.getdaysinmonth(datetime.getyear($birthday), datetime.getmonth($birthday))} days
Birthday year had {datetime.getdaysinyear(datetime.getyear($birthday))} days
Your age: {datetime.calculateage($birthday, "2008-08-01T16:33:00" )}

Birthday: 1973-12-12T10:10:00
Day of week born: Wednesday
Day of month born: 12 
Day of year born: 346
Birthday month had 31 days
Birthday year had 365 days
Your age: 34