The following code example is taken from the book
C++20 - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2021
The code is licensed under a Creative Commons Attribution 4.0 International License. Creative Commons License

// raw code

export module Mod3;       // module declaration

export import :Customer;  // import and export interface partition Customer
//... // import and export other interface partitions