Calling functions from other files/modules

[Namal via Digitalmars-d-learn]

On Wednesday, 6 January 2016 at 23:06:38 UTC, Adam D. Ruppe wrote:
> On Wednesday, 6 January 2016 at 23:00:43 UTC, Namal wrote:
>> I just tried to import one module with a main into another, 
>> but I get this:
>
> You can't have two mains, but you can import a module with main 
> from another module without one.

How can I produce a program file from that module which has no 
main but uses some functions from main module?