Kivy: how to update a bool outside class

The bool is currently updated when I click on and off the checkbox however when I click the button it will always print the default value I define at the start. How can I update a bool that is outside the class, so that when I click the button and call the function, it updates the bool?

Also, how can I call a function like this when clicking the button, that is outside of the class?

Thanks

someBool = False


def someFunction():
    print(someBool)



class MyGridLayout(GridLayout):
    def __init__(self, **kwargs):
        #grid layout constructor
        super(MyGridLayout, self).__init__(**kwargs)

        #set columns for the layout
        self.cols = 2

        self.add_widget(Label(text="checkbox"))
        self.checkbox= CheckBox(active = False)
        self.add_widget(self.checkbox)

        #this will bind the label and checkbox
        self.checkbox.bind(active = self.checkboxActive)

        self.button= Button(text="Button")
        self.button.bind(on_press=someFunction)
        self.add_widget(self.button)

    def checkboxActive(self, checkbox, value):
        if value:
            someBool = True
        else:
            someBool = False


class MyApp(App):
    def build(self):
        return MyGridLayout()


if __name__ == '__main__':
    MyApp().run()