TypeScript lodash `isString()` typeguard usage

retool-typescript-control-flow-analysis-9.ts

import { isString } from "lodash"

let name: string | undefined = "John"
// `name` is of type `string | undefined`

let price: number | undefined = 1
// `price` is of type `number | undefined`

if (isString(name)) {
  name
  // `name` is of type `string` 

} else if (isString(price)) {
  price
  // `price` is of type `never`

}