Sharing controller between views

I have a frame which holds 2 views. I want to use a common controller for both of them but not instantiate 2 controllers. How do i achieve this? Singleton? Send the controller as an argument?

This is what i want

First view

Class ViewAlpha
    def __init_(self, parent):
        self.controller = Controller()

    def on_click(self, event):
        self.controller.do_this(event.data)

Second view

Class ViewBeta
    def __init_(self, parent):
        self.controller = Controller()

    def on_click(self, event):
        self.controller.do_this(event.data)

Controller

Class Controller
    def __init_(self):
        self.client = Client()

    def do_this(self, data):
        self.client.store(data)