new stored procedure with OUT parameters

Hi all,

I was playing around with the stored procedure support in v11 and found
that pure OUT parameters are not supported. Is there any reason we only
support INOUT but not OUT parameters?

psql (11.0 (Homebrew petere/postgresql))
dev=# CREATE PROCEDURE test_sp(a OUT int) LANGUAGE plpgsql AS $$
dev$# BEGIN
dev$# a = 5;
dev$# END; $$;
ERROR: procedures cannot have OUT arguments
HINT: INOUT arguments are permitted.

Thanks,
Anton