I find this custom driver on templates / python / driver_functions and I did it run.
But I realize that always I close and reopen the file, it need to be compiled and updated in the driver.
I try this but it doesn't compile in the open file and also I don't know how to update all dependencies after
import bpy
import os
import sys
if __name__ == "__main__":
path = "F:/fILES/proyectos/bpy_study/Scripts"
fname01 = "driver_functions.py"
if path not in sys.path:
sys.path.append(path)
file01 = os.path.join(path, fname01)
exec(compile(open(file01).read(), fname01, 'exec'))