input: Write a python function to create a simple GUI with two buttons using tkinter library.
  assert func1() == None
  assert func2() == None
output: def create_gui():
      import tkinter as tk
  
      def on_button1_click():
          print("Button 1 clicked")
  
      def on_button2_click():
          print("Button 2 clicked")
  
      root = tk.Tk()
      root.title("Simple GUI")
  
      button1 = tk.Button(root, text="Button 1", command=on_button1_click)
      button1.pack()
  
      button2 = tk.Button(root, text="Button 2", command=on_button2_click)
      button2.pack()
  
      root.mainloop()