title: NameError: name 'tk' is not defined in the object class
body: <p>I have constructed an application, the source starts like this:</p>
  
  <pre><code>from tkinter import Text
  from tkinter import Label    
  
  from AESEncDec import *
  from MD5Hashing import *
  from RSAEncDec import *
  
  color = 'lightblue' #color our background
  
  class Application(Frame):
  
      def __init__(self, root=None):
  
          Frame.__init__(self, root)
          self.frame_width = 700
          self.frame_height = 400
  </code></pre>
  
  <p>But last piece of it cannot execute:</p>
  
  <pre><code>#create object TK class
  the_window = Tk(className = " Cryptographic")
  #create object Application
  app = Application(the_window)
  #run our Application
  app.mainloop()
  </code></pre>
  
  <p>And it gives the NameError:</p>
  
  <blockquote>
    <p>Traceback (most recent call last):
      File "/home/artur/Documents/MScProject/MSc Project/Task #179276/main_program.py", line 169, in 
        the_window = Tk(className = " Cryptographic")
    NameError: name 'Tk' is not defined</p>
  </blockquote>
  
  <p>How should I define it properly in this case?</p>