Get the most recent weight sample.On success, the callback function will be provided with a `weight` object containing the weight `value`, and the `startDate` and `endDate` of the weight sample. *Note: startDate and endDate will be the same as weight samples are saved at a specific point in time.*```javascriptletoptions={unit:'pound'};``````javascriptAppleHealthkit.getLatestWeight(options,(err:string,results:Object)=>{if(err){console.log("error getting latest weight: ",err);return;}console.log(results)});``````javascript{value:200,startDate:'2016-07-08T12:00:00.000-0400',endDate:'2016-07-08T12:00:00.000-0400'}```