Nested funtion

Hi

Is there any way to create nested function?

oracle to postgres migration required super function variable reference
into nested function without nested function parameter

Oracle sample:
-------------------------------
create or replace function f1(n number) return number
is
vs number:=1;
function nf1(m number) return number is
begin
return vs + m + n;
end;
begin
return nf1(2);
end;
/

run:
--------
SQL> select f1(9) from dual;

F1(9)
----------
12

Thanks
Sridhar BN