Modulation of Lua scripting plane 4.5.7

Hello,
I work on a project that runs on Pixhawk, and all the control and guidance loops are implemented using Lua scripting.
As the project is getting big, we are looking for a way to make it modular, containing an individual script for each section in the project, and a separate main script.
what is the best way to do it?
Firmware: Plane 4.5.7
Hardware: Cube Orange

lua supports loading files in script.

how can I do it? what is the syntax?
I use plane 4.5.7 and require doesn’t work.
thank you in advance.

In the source code for scripting library there is docs.lua file that contains all the ardupilot bindings.