code: def null(alphabet):
  	'''
  		An FSM accepting nothing (not even the empty string). This is
  		demonstrates that this is possible, and is also extremely useful
  		in some situations
  	'''
  	return fsm(
  		alphabet = alphabet,
  		states   = {0},
  		initial  = 0,
  		finals   = set(),
  		map      = {
  			0: dict([(symbol, 0) for symbol in alphabet]),
  		},
  	f null(alphabet):
  	'''
  		An FSM accepting nothing (not even the empty string). This is
  		demonstrates that this is possible, and is also extremely useful
  		in some situations
  	'''
  	return fsm(
  		alphabet = alphabet,
  		states   = {0},
  		initial  = 0,
  		finals   = set(),
  		map      = {
  			0: dict([(symbol, 0) for symbol in alphabet]),
  		},
  	)
docs: An FSM accepting nothing (not even the empty string). This is
  		demonstrates that this is possible, and is also extremely useful
  		in some situations