[CHALLANGE] Add seconds to a date

I tried to make a PLSQL (oracle) function in order to add some seconds
to a specified date:

Let's take a exemple:
New_date=sec2date(#2002-02-02#, 100),
this should add 100 seconds to the entered date:
this should then return "2002-02-02 00:01:40".

Attention to the lead year.

If any one wants to take this challage or propose some quick wins
idees