create table test_me ( 
  a_name varchar2(10) not null, 
  a_value number(1) not null 
)

create or replace 
function tm_ins( p_name in test_me.a_name%TYPE ) 
  return test_me.a_value%TYPE 
as 
begin 
  return null; 
end;

declare 
  l_n number; 
begin 
  dbms_output.put_line( 'test 1="' || tm_ins( null ) || '"'); 
end;