code: def is_valid_address (s):
      
      try:
          pairs = s.split (":")
          if len (pairs) != 6: return False
          if not all(0 <= int(b, 16) <= 255 for b in pairs): return False
      except:
          return False
      return True
docs: returns True if address is a valid Bluetooth address
  
      valid address are always strings of the form XX:XX:XX:XX:XX:XX
      where X is a hexadecimal character.  For example,
          01:23:45:67:89:AB is a valid address, but
          IN:VA:LI:DA:DD:RE is not