text: -- toggle_star stars on unstars a given package for the provided user.
  create or replace function toggle_star(p_user_id uuid, p_package_id uuid)
  returns void as $$
  declare
      v_already_starred boolean;
  begin
      select exists (
          select * from user_starred_package
          where user_id = p_user_id and package_id = p_package_id
      ) into v_already_starred;
  
      if not v_already_starred then
          insert into user_starred_package (user_id, package_id)
          values (p_user_id, p_package_id);
  
          update package set stars = stars + 1 where package_id = p_package_id;
      else
          delete from user_starred_package
          where user_id = p_user_id and package_id = p_package_id;
  
          update package set stars = stars - 1 where package_id = p_package_id;
      end if;
  end
  $$ language plpgsql;
  