old_contents: from random import randint
  from subprocess import call
  
  
  def set_wifi(network_interface, status):
      """Turns off the wifi.
      
      Takes a string like 'wlan0' and a status like 'up' or 'down'.
      """
      if status in ['up', 'down']:
          call(['sudo', 'ip', 'link', 'set', 'dev', network_interface, status])
  
  def dec_to_hex(n):
      """Takes a decimal number from 0 to 15 and returns the corresponding hex digit."""
      return(hex(n)[2:])
  
  def get_hex_pair():
      """Returns a pair of hex digits as a string like: '5f'."""
      x = str(dec_to_hex(randint(0, 15)))
      y = str(dec_to_hex(randint(0, 15)))
      return x + y
  
  def generate_mac():
      """Returns a randomly generated MAC address.
      
      Example format: '4a:bb:19:9f:3c:cf'.
      """
      mac_address = ':'.join([get_hex_pair() for _ in range(6)])
      return mac_address
  
  def get_mac():
      pass
  
  def set_mac(address):
      pass
  
  if __name__ == '__main__':
      set_wifi('wlan0', 'down')
  
      set_wifi('wlan0', 'up')
  
new_contents: from random import randint
  from subprocess import call
  
  
  def set_wifi(network_interface, status):
      """Turns the wifi on or off.
      
      Takes a string like 'wlan0' and a status like 'up' or 'down'.
      """
      if status in ['up', 'down']:
          call(['sudo', 'ip', 'link', 'set', 'dev', network_interface, status])
  
  def dec_to_hex(n):
      """Takes a decimal number from 0 to 15 and returns the corresponding hex digit."""
      return hex(n)[2:]
  
  def get_hex_pair():
      """Returns a pair of hex digits as a string like: '5f'."""
      x = str(dec_to_hex(randint(0, 15)))
      y = str(dec_to_hex(randint(0, 15)))
      return x + y
  
  def generate_mac():
      """Returns a randomly generated MAC address.
      
      Example format: '4a:bb:19:9f:3c:cf'.
      """
      mac_address = ':'.join([get_hex_pair() for _ in range(6)])
      return mac_address
  
  def get_mac():
      pass
  
  def set_mac(address):
      pass
  
  if __name__ == '__main__':
      set_wifi('wlan0', 'down')
  
      set_wifi('wlan0', 'up')
  
subject: Fix typos