=== /a.js ===
/**
 * @typedef MyType
 * @property {sting} [x]
 */

/** @param {MyType} p  */
export function f(p) { }
>f : Symbol(f, Decl(a.js, 0, 0))
>p : Symbol(p, Decl(a.js, 6, 18))

=== /b.js ===
import { f } from "./a.js"
>f : Symbol(f, Decl(b.js, 0, 8))

f({ x: 42 })
>f : Symbol(f, Decl(b.js, 0, 8))
>x : Symbol(x, Decl(b.js, 1, 3))

