input: Write a python function to create a tkinter window with a button that displays "Button was pressed!" when clicked.
  assert create_window() is None
output: def create_window():
      import tkinter as tk
  
      def on_button_click():
          print("Button was pressed!")
  
      root = tk.Tk()
      button = tk.Button(root, text="Press me", command=on_button_click)
      button.pack()
  
      root.mainloop()