Check a jsonb column is an array of arrays

is_AoA.sql

create or replace function is_AoA(_input jsonb, out _out boolean) as $$
  begin
    select into _out 't'::boolean=all(array_agg(jsonb_typeof(v)='array')) from jsonb_array_elements(_input) as v;
  end;
$$ language plpgsql;

create table mytest (
  id bigserial primary key,
  myAoA jsonb check (is_AoA(myAoA))
);