How to access Python Variables from parent Tkinter

I have a Tkinter App and currently I am trying to split the code from each tab to be on each tab. I can pass the string as a parameter into the Tab but is it possible to access the parent variables from the child ttk.Frame ? The actual code has more things.

class Tab(ttk.Frame):
    def __init__(self, master):
        super().__init__(master)
    def PrintThings(self):
        Print(self._A) ##How can I access here self._A to print Hello World

class App():
    def __init__(self):
        self._A = "Hello World"
        self._root = Tk()
        self._root.geometry("800x1200")
        self._TabContainer = ttk.Notebook(self._root)
        self._Tab = Tab(self._TabContainer)

    def main(self):
        self._Tab.pack()

App.main() 

Answer

The easiest solution is to pass the instance of App to each tab. With that, the tab has access to anything defined in App.

It looks something like this:

class App():
    ...
    self._Tab = Tab(self._TabContainer, app=self)
    ...
...
class Tab(ttk.Frame):
    def __init__(self, master, app):
        self.app = app
        ...

    def PrintThings(self):
        print(self.app._A)