How to properly use namespace with external modules in TypeScript?

Hi! I'm learning TypeScript and trying to structure my project. Previously I used namespaces to organize code within a single file, but now that the project has grown, I want to split the code into separate modules (files). The problem is that when I try to import a module that contains a namespace, I get errors or the namespace doesn't work as I expect. Here's an example of what I'm doing: I have a file `math.ts`: ```typescript namespace MathUtils { export function add(a: number, b: number): number { return a + b; } export function subtract(a: number, b: number): number { return a - b; } } ``` And a file `app.ts`: ```typescript import { MathUtils } from './math'; console.log(MathUtils.add(5, 3)); // Error: Mat