How to pass text from MDTextFieldRect to a function?

Question

Python

Tell me, please, I have already rummaged through everything that is possible
. How can I transfer its contents from MDTextFieldRect (located in the main.kv file) after pressing the "Enter" key to the input function in the main.py file?

main.py file

from kivymd.app import MDApp
from kivy.uix.boxlayout import BoxLayout
from kivymd.uix.textfield import MDTextFieldRect

class Container(BoxLayout):
    pass

class MainApp(MDApp):
    def input(self, value):
        Snackbar(text=value).open()

    def build(self):
        all = Container()
        return all

MainApp().run()

Main.kv file

#:import MDField kivymd.uix.textfield
<Container>:
    orientation: "vertical"
       
    MDTextFieldRect:
        multiline: False
        text: 'text'
        on_text_validate:  app.input()

Answer 1

Through f = open () did not try?