text: exports.sequential = async (f, items) => {
    const go = async (f, all, items, i) => {
      if (i >= items.length) {
        return all;
      }
  
      const one = items[i];
      const value = await f(one);
      all.push(value);
      return go(f, all, items, i + 1);
    };
    return go(f, [], items, 0);
  };
  