from tkinter import Label, Button
blink = 0

class MyClass(tk.Frame):
    def __init__(self, master):
        self.master = master
        super().__init__(self.master)

        global blink  

        self.label = Label(master, text=blink)
        self.button = Button(master, text="Button", command=lambda: foo(self.label))
        self.label.pack()
        self.button.pack()
        #self.blinkCheck()

    def blinkCheck(self):
        global blink
        while True:
            print("blink in blinkCheck method is = {}".format(blink))
            time.sleep(2.5)

    def foo(self, label):
        label.config(text=blink)