Question: call function from different snapshot

Let's say I have a snapshot main.ss and a snapshot helpers.ss, and the code in main.ss wants to call functions from helpers.ss.
I tried merging main.ss and helpers.ss, but main.ss is not able to call the functions from helpers.ss.

So, is there any way to call functions defined in helpers.ss from code in main.ss? Or even better, just include functions form helper.js in main.js?