Char Functions Oracle PLSQL

SQL>
SQL> create or replace function total_compensation(
  2    p_salary number,
  3    p_commission number ) return number
  4  deterministic as
  5  begin
  6    return nvl(p_salary,0) + nvl(p_commission,0);
  7  end total_compensation;
  8  /
Function created.
SQL>
SQL> select total_compensation(1,2) from dual;
TOTAL_COMPENSATION(1,2)
-----------------------
                      3
SQL>