Accessing stage/global functions inside a class?

Hello !

I have a .as file with a load of functions that i include using : include “myFunctions.as”. They can be accessed alright.
I have a custom class that extends movieclip, and i want to use a function inside that class that is located in my “myFunctions.as” file.
How do i do that? Seems like the class loads before the myFunctions.as file so the functions are unavailable at this time. I get that error message :

1180: Call to a possibly undefined method [function name].