HowdoIpositionanimageinkivyusingkvfile

I'm trying to place an image on the border of the screen, how can I do this using the kv file?

Code:

import kivy

kivy.require("1.9.0")

from kivy.app import App
from kivy.uix.image import *

class Test(App):
    pass

Test().run()

Kv File:

Image:

    source: 'logo.png'