Unit in options has error

[rhit-tianr]

Hi, I followed the format on the website and tried to set the unit of the data, but it will have an error saying its type is not assignable.
My code is:

let options = {
unit:'pound',
startDate: new Date(2017, 0, 0).toISOString(), // required
endDate: new Date().toISOString(), // optional; default now
ascending: true, // optional; default false
};

  AppleHealthKit.getWeightSamples(
    options,
    (err: Object, results: Array<HealthValue>) => {
      if (err) {
        return;
      }
        return {
          console.log(JSON.stringfy(results))
        }
    },
  );

And it will indicate there is an error in options:

Argument of type '{ unit: string; startDate: string; endDate: string; ascending: boolean; }' is not assignable to parameter of type 'HealthInputOptions'.
Types of property 'unit' are incompatible.
Type 'string' is not assignable to type 'HealthUnit | undefined'.ts(2345)

And this not only shows the error on getWeightSamples(), but other functions are also not able to set units. Does anyone know how to fix it?