I'm trying to add a function that will be accessible throughout all parts of my program. I want something like:

def GlobalFunctions.my_function(x,y)
    puts x + y
end

to be accessible for all models. Specifically I am trying to use a function like this in my seeds.rb file but I am most likely going to be reusing the code and don't want any redundancy. Now I know I can make a simple class, but I could also make a module. What are some reasons to go in either direction? And once I've decided on which type to use, how do I make it accessible throughout the whole program?

I have tried a module, but I keep getting " Expected app/[module file] to define [ModuleName]"