class Time
def Time.validate(year, month=1, day=1,
hour=0, min=0, sec=0, usec=0)
require "date"
begin
d = Date.new(year,month,day)
rescue
return nil
end
Time.local(year,month,day,hour,min,sec,usec)
end
end
t1 = Time.validate(2000,11,30) # Instantiates a valid object
t2 = Time.validate(2000,11,31) # Returns nil