input: Write a python function to create a simple GUI with a text input and a button to display the entered text.
  assert "Enter your input:" in create_gui_code()
  assert "Submit" in create_gui_code()
  assert "You entered:" in create_gui_code()
output: def create_gui_code():
      import tkinter as tk
      from tkinter import messagebox
  
      def show_text():
          entered_text = entry.get()
          messagebox.showinfo("You entered:", entered_text)
  
      root = tk.Tk()
      root.title("Simple GUI")
  
      label = tk.Label(root, text="Enter your input:")
      label.pack()
  
      entry = tk.Entry(root)
      entry.pack()
  
      button = tk.Button(root, text="Submit", command=show_text)
      button.pack()
  
      root.mainloop()