old_contents: import tkinter as tk
  import tk_tools
  
  from tk_tools.images import rotary_gauge_volt
  
  root = tk.Tk()
  
  p1 = tk_tools.RotaryScale(root, max_value=100.0, size=100, unit='km/h')
  p1.grid(row=0, column=0)
  
  p2 = tk_tools.RotaryScale(root,
                            max_value=100.0,
                            size=100,
                            needle_thickness=3,
                            needle_color='black',
                            img_data=rotary_gauge_volt)
  
  p2.grid(row=0, column=1)
  
  increment = 1.0
  value = 0.0
  
  
  def inc():
      global value
      value += increment
  
      p1.set_value(value)
      p2.set_value(value)
  
  
  def dec():
      global value
      value -= increment
  
      p1.set_value(value)
      p2.set_value(value)
  
  
  inc_btn = tk.Button(root,
                      text='increment by {}'.format(increment),
                      command=inc)
  
  inc_btn.grid(row=1, column=0, columnspan=2, sticky='news')
  
  dec_btn = tk.Button(root,
                      text='decrement by {}'.format(increment),
                      command=dec)
  
  dec_btn.grid(row=2, column=0, columnspan=2, sticky='news')
  
  root.mainloop()
  
new_contents: import tkinter as tk
  import tk_tools
  
  from tk_tools.images import rotary_gauge_volt
  
  
  def inc():
      global value
      value += increment
  
      p1.set_value(value)
      p2.set_value(value)
  
  
  def dec():
      global value
      value -= increment
  
      p1.set_value(value)
      p2.set_value(value)
  
  
  if __name__ == '__main__':
  
      root = tk.Tk()
  
      p1 = tk_tools.RotaryScale(root, max_value=100.0, size=100, unit='km/h')
      p1.grid(row=0, column=0)
  
      p2 = tk_tools.RotaryScale(root,
                                max_value=100.0,
                                size=100,
                                needle_thickness=3,
                                needle_color='black',
                                img_data=rotary_gauge_volt)
  
      p2.grid(row=0, column=1)
  
      increment = 1.0
      value = 0.0
  
      inc_btn = tk.Button(root,
                          text='increment by {}'.format(increment),
                          command=inc)
  
      inc_btn.grid(row=1, column=0, columnspan=2, sticky='news')
  
      dec_btn = tk.Button(root,
                          text='decrement by {}'.format(increment),
                          command=dec)
  
      dec_btn.grid(row=2, column=0, columnspan=2, sticky='news')
  
      root.mainloop()
  
subject: add if __name__ == '__main__':