PL/SQL functions: Iterate and keys for associative arrays

Unfortunately associative arrays still require more “coding”:
we still can’t use “indices of” or “values of” in simple FOR(though they are available for FORALL for a long time), don’t have convinient iterators and even function to get all keys…
That’s why I want to show my templates for such things like iterator and keys function. You can adopt these functions and create them on schema level.

declare 
   type numbers  is table of number;
   type anumbers is table of number index by pls_integer;
   a anumbers;
   i pls_integer;

   function iterate( idx in out nocopy pls_integer, arr in out nocopy anumbers) 
      return boolean
   as pragma inline;
   begin
      if idx is null 
         then idx:=arr.first; 
         else idx:=arr.next(idx);
      end if;
      return idx is not null;
   end;

  function keys(a in out nocopy anumbers) return numbers as
     res numbers:=numbers();
     idx number;
     pragma inline;
  begin
     while iterate(idx,a) loop
        res.extend;
        res(res.count):=idx;
     end loop;
     return res;
  end;

begin
   a(1):=10;
   a(3):=30;
   a(5):=50;
   a(8):=80;
   -- iterate:
   while iterate(i,a) loop
      dbms_output.put_line(a(i));
   end loop;

   -- keys:
   for i in 1..keys(a).count loop
      dbms_output.put_line(a(keys(a)(i)));
   end loop;

end;