title: tkinter cannot get attribute from self
body: <p>I have an error that it cannot get the attribute self.story1 , self.story2...
  but self.window object does not call an error. why is it showing me an error?</p>
  <pre><code>from tkinter import *
  
  class Main(Frame):
      def __init__(self, master=None):
          super().__init__()
  
          self.window = master
          self.__setwindow__()
  
          &quot;schedule list&quot;
          self.story1 = [&quot;&quot;]
          self.story2 = [&quot;&quot;]
          self.story3 = [&quot;&quot;]
          self.story4 = [&quot;&quot;]
  
      def __setwindow__(self):
          self.window.geometry(&quot;300x500&quot;)
  
          self.title = Label(text=&quot;오늘 할일을 작성하시오.&quot;)
          self.title.place(x=80, y=30)
  
          for a,b,c,d in [len(i) for i in [self.story1, self.story2, self.story3, self.story4]]:
              print(a,b,c,d)
  
  ob = Tk()
  Main(master = ob)
  ob.mainloop()
  </code></pre>