This is my code:

```
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.lang import Builder
from kivy.properties import NumericProperty

Builder.load_string('''
<Simple>:
    Label:
        text: str( root.sometext )
    Button:
        text: '+++'
        on_release: root.inc()
''')

class Simple(BoxLayout):
    sometext = NumericProperty(0)

    def __init__(self, **kwargs):
        super(Simple, self).__init__(**kwargs)

        self.sometext = 5

    def inc(self):
        self.sometext += 5 

class TApp(App):
    def build(self):
        return Simple()

TApp().run()

```

Everything is working, every time when button is presses label is updated by 5.

What I wont to add is some animation.
Like: before update number goes to left, and when updated number comes from right.
If this is animation complicated, others concept are welcomed.

How can it be done ?
I looked documentation but every example is with postion, not with text update (or at least what I have found).