 CREATE OR REPLACE FUNCTION isLeapYear(i_year NUMBER) RETURN boolean AS
 BEGIN
      IF mod(i_year, 400) = 0 OR ( mod(i_year, 4) = 0 AND mod(i_year, 100) != 0) THEN
       return TRUE;
    ELSE 
       return FALSE;
    END IF;
 END;
__________________________________________

 BEGIN
   IF isLeapYear(2004) THEN
      dbms_output.put_line('Yes, it is a leap year');
   ELSE
      dbms_output.put_line('No, it is not a leap year');
   END IF;
 END;