validDmy
fun validDmy(day: <Error class: unknown class>, month: DateMonth, year: <Error class: unknown class>): Boolean
Returns true if the day-month-year triplet forms a valid, existing day in the range of days #GDate understands (Year 1 or later, no more than a few thousand years in the future).
Return
true if the date is a valid one
Parameters
day
day
month
month
year
year