title: How to set the argument for iconbitmap()?
body: <p>I am creating an image viewer. But, I don't know how to set the argument for iconbitmap.</p>
  
  <p>I have tried bitmap, default but it says default is not defined.</p>
  
  <pre><code>def open_to_browse():
      global my_image
      mainframe1.filename = filedialog.askopenfilename(initialdir=home, title="Select a file", filetypes=(("*.png"),("*.jpeg")))
      my_label = tk.Label(mainframe1, text=mainframe1.filename)
      my_image = ImageTk.PhotoImage(Image.open(mainframe1.filename))
      my_image_label = tk.Label(image = my_image)
  
  import os
  import tkinter as tk
  from tkinter import filedialog
  from PIL import ImageTk
  from PIL import Image
  
  home = os.getcwd()
  #print(home)
  
  mainframe1 = tk.Tk()
  mainframe1.title("Image Viewer")
  mainframe1.iconbitmap(bitmap= "NoneType:None", default= "NoneType:None")
  
  button = tk.Button(mainframe1, text="Open the file", command=open_to_browse)
  
  my_label.grid(row=0, column=1, sticky=tk.W, pady=4)
  button.grid(row=1, column=1, sticky=tk.W, pady=4)
  my_image_label.grid(row=2, column=1, sticky=tk.W, pady=4)
  
  mainframe1.mainloop()
  </code></pre>