UNNEST and multidimensional arrays

Hi
Is there anyway to control how many levels unnest unnests?
ie: if I have (in perl) an array of arrays for unnest to only unnest the
top level, leaving the sub levels as an array, so a select would show
{val1,val2}
{val1,val2}
{val1,val2}
rather than
val1
val2
val1
val2
val1
val2

Currently I am using a variation of the fooling code from postgres wiki
(from 2013)

https://wiki.postgresql.org/wiki/Unnest_multidimensional_array

CREATE OR REPLACE FUNCTION public.reduce_dim(
anyarray)
RETURNS SETOF anyarray
LANGUAGE 'plpgsql'

COST 100
VOLATILE
ROWS 1000
AS $BODY$
DECLARE s $1%type;
BEGIN
IF cardinality ($1::text[]) >0 THEN
FOREACH s SLICE 1 IN ARRAY $1 LOOP
RETURN NEXT s;
END LOOP;
END IF;
RETURN;
END;
$BODY$;

thanks in advance

Mike