code: function descriptorOf(object, name) {
    const descriptor = Object.getOwnPropertyDescriptor(object, name);
    if (descriptor) {
      return descriptor;
    } else {
      const proto = prototypeOf(object);
      if (proto) {
        return descriptorOf(proto, name);
      } else {
        return null;
      }
    }
  }
docs: /*~
  Returns the descriptor searching upwards the prototype chain.