How to exclude function from being imported in D language?

[BoQsc via Digitalmars-d-learn]

Premise: In D language, only one main(){} function can exist in a 
program.
Having two `main()` functions throws an error.

Let's say I want to use some functionality of another program, 
but it has a `main(){}`
function. How can I import and use functions without importing 
the `main(){}` function?