title: NameError: global name 'text' is not defined
body: <p>I have a python code snippet that coverts the Mac address to another code using caesar ciphertext: The code is given below:</p>
  
  <pre><code>import uuid
  def getmac():
    mac_num = hex(uuid.getnode()).replace('0x', '').upper()
    mac = ''.join(mac_num[i : i + 2] for i in range(0, 11, 2))
    return mac
  
  plaintext = getmac()
  alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
  key = 1
  cipher = ''
  
  for c in plaintext:
      if c in alphabet:
        cipher += alphabet[(alphabet.index(c) + key +3)%(len(alphabet))]
  print('Code:' + cipher)
  </code></pre>
  
  <p>This works proper as it prints out the code to the Python shell, however when i Edit the same code with  TKinter library, I get concatenation  and other errors , The code used in TKinter lib is given below:
  In this snippet the function of the program is same ,however i just want the mac address to be input from the user and when he clicks on submit ,the code is prompted to him:</p>
  
  <pre><code>import uuid
  from Tkinter import *
  
  root = Tk()
  
  root.title("Code Generator")
  root.geometry("250x200+200+100")
  root.resizable(width=False, height=False)
  cipher = ''
  
  
  Label(root, text='Mac Address:').grid(row=0, sticky=W, padx=4)
  Entry(root).grid(row=0, column=1, sticky=E, pady=4)
  
  Label(root, text="Code:").grid(row=1, sticky=W, padx=4)
  hlbl = Label(root, text=cipher,  width=20)
  hlbl.grid(row=0, column=2, sticky=E, pady=4)
  
  
  def get_it():
   alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    for c in text:
      if c in alphabet:
        cipher += alphabet[(alphabet.index(c) + key + 2) % (len(alphabet))]
  
  Button(root, text="Submit", command=get_it).grid(row=2, column=1)
  root.mainloop()
  </code></pre>
  
  <p>when i run the program i get this:<br>
  <a href="https://i.stack.imgur.com/fR8ol.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fR8ol.jpg" alt="enter image description here"></a><br>
  When i enter a random text and click submit i get this:<br>
  <a href="https://i.stack.imgur.com/Tbzn8.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Tbzn8.jpg" alt="enter image description here"></a><br>
  What changes should i make?</p>