First file

hello.hemhem

import { greeting } from "./copy"        // a plain .ts module

let greet = (name: string) => `${greeting}, ${name}`
console.log(greet("world"))

hello.ts — generatedts

import { greeting } from "./copy";

const greet = (name: string) => `${greeting}, ${name}`;
console.log(greet("world"));

In this example, the import resolves against the .d.ts file, the emitted file uses standard TypeScript syntax, and the TypeScript compiler verifies the output.