How to work with multiple files and tkinter?

[philipbergwerf]

I have a beginners question about importing files and not being able to use a function in this file because it can't 'look back'.

I have two files. main.py:

from tkinter import *
from function import drawLine
master = Tk()

canvas_width = 80
canvas_height = 40
w = Canvas(master, 
           width=canvas_width,
           height=canvas_height)
w.pack()

y = int(canvas_height / 2)

drawLine()

mainloop()

and function.py:

def drawLine():
	w.create_line(0, y, canvas_width, y, fill="#476042")

I understand that 'function.py' cannot look into 'main.py'. How to write a function in 'function.py' that draws a line in the 'main.py' canvas? I hope someone can teach me about the way people work usually with drawing something on a canvas that is in another file :)