Regular expression

def match1(p, text):
	if not text: return False
	return p == '.' or p == text[0]

def match_star(p, pattern, text):
	return (match(pattern, text) or
			(match(p, text) and
				match_star(p, pattern, text[1:])))

print test()

api

def lit(string):  return ('lit', string)
def seq(x, y):    return ('seq', x, y)
def alt(x, y):    return ('alt', x, y)
def star(x):      return ('star', x)
def plus(x):      return seq(x, star(x))
def opt(x):       return alt(lit(''), x) #opt(x) means that x is optional
def oneof(chars): return ('oneof', tuple(chars))
dot = ('dot',)
eol = ('eol',)

def search(pattern, text):
	for i in range(len(text)):
		m = match(pattern, text[i:])
		if :
			return m

def match(pattern, text):
	remainders = matchset(pattern, text)
	if remainders:
		shortest = min(remainders, key=len)
		return

def components(pattern):
	x = pattern[1] if len(pattern) > 1 else None
	y = pattern[2] if len(pattern) > 2 else None
	return pattern[0], x, y

def matchset(pattern, text):
	elif 'seq' == op:
		return set(t2 for t1 in matchset(x, text) for t2 in matchset(y, t1))

def seq(x, y) return lambda text: set().union(*map(y, x(text)))

def alt(x, y) return lambda text: x(text) | y(ext)

def genseq(x, y, Ns):
	Nss = range(max(Ns)+1)
	return set(m1 + m2
		for m1 in x(Nss) for m2 in y(Nss)
		if len(m1 + m2) in Ns)